NTIA Report 00-378

Spectrum Usage

for the Fixed Services

Robert J. Matheson

U.S. DEPARTMENT OF COMMERCE

William M. Daley, Secretary

Gregory L. Rohde, Assistant Secretary

for Communications and Information

March 2000
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iii

Acknowledgments

The author would like to acknowledge Bob Wilson, NTIA Office of Spectrum Management, for preparing

maps, graphs, and Federal frequency assignment summaries and to thank Comsearch for providing

historical data and current frequency license summaries for non-Government frequency bands. In addition,

the author would like to thank many industry and Government experts who shared information freely and

provided much helpful advice in the preparation of this report.

Disclaimer

Certain products, technologies, and corporations are mentioned in this report to describe aspects of the

ways that microwave bands are used at present or may be used in the future. The mention of such entities

should not be construed as any endorsement, approval, recommendation, prediction of success, or that they

are in any way superior to or more noteworthy than similar entities that were not mentioned.
iv

CONTENTS

FIGURES ............................................................. vi

ABBREVIATIONS ....................................................... vii

EXECUTIVE SUMMARY ................................................... x

ABSTRACT ............................................................. 1

1. UPDATE OF RECENT HISTORY IN MICROWAVE USAGE .......................... 1

1.1 Introduction ..................................................... 1

1.2 Cellular/PCS Growth ............................................... 2

1.3 Deployment of Optical Fiber .......................................... 3

1.4 Fiber versus Microwave in Wide Bandwidth Future Applications ................... 4

1.5 High Density Fixed Systems .......................................... 5

1.6 Unlicensed Spread Spectrum Systems in ISM and U-NII Bands .................... 6

1.7 Reallocation and Rechannelization in the 2 GHz Migration Bands ................... 7

1.8 Release of 255 MHz of Federal Spectrum .................................. 9

1.9 Allocation of 2 GHz Spectrum for Mobile Satellite Service (MSS) ................. 10

2. SUMMARY OF CURRENT BAND-BY-BAND USE ............................... 11

2.1 Methodology and Approach .......................................... 11

2.1.1 Geographical and Statistical Data ............................... 12

2.1.2 Geographical Maps ........................................ 12

2.1.3 Statistical Tables .......................................... 13

2.1.4 License Density Statistics Graph ................................ 15

2.1.5. User Bandwidth Graph ...................................... 16

2.1.6 Typical Users ............................................ 18

2.1.7 Recent Trends in Number of Assignments .......................... 18

2.1.8 Comments .............................................. 19

2.1.9 Estimated Future Growth Rate ................................. 19

2.2 Usage in the 406.1-420 MHz Band ..................................... 20

2.3 Usage in the 928-929 MHz and 952-952.85 MHz Bands ....................... 22

2.4 Usage in the 932-935 MHz and 941-944 MHz Bands .......................... 24

2.5 Usage in the 944-952 MHz Band ...................................... 26

2.6 Usage in the 952.85-960 MHz Band .................................... 28

2.7 Usage in the 1350-1400 MHz Band ..................................... 30

2.8 Usage in the 1427-1435 MHz Band ..................................... 32

2.9 Usage in the 1710-1850 MHz Band ..................................... 34

2.10 Usage in the 1850-1990 MHz Band .................................... 36

2.11 Usage in the 1990-2110 MHz Band .................................... 38

2.12 Usage in the 2110-2130 MHz and 2160-2180 MHz Bands ...................... 40

2.13 Usage in the 2130-2150 MHz and 2180-2200 MHz Bands ...................... 42

2.14 Usage in the 2150-2160 MHz Band .................................... 44

2.15 Usage in the 2200-2300 MHz Band .................................... 46

2.16 Usage in the 2450-2483.5 MHz Band ................................... 48

2.17 Usage in the 2500-2690 MHz Band .................................... 50
v

2.18 Usage in the 3700-4200 MHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

2.19 Usage in the 4400-4990 MHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

2.20 Usage in the 5925-6425 MHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

2.21 Usage in the 6525-6875 MHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

2.22 Usage in the 6875-7125 MHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

2.23 Usage in the 7125-8500 MHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

2.24 Usage in the 10.55-10.68 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

2.25 Usage in the 10.7-11.7 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

2.26 Usage in the 12.2-12.7 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

2.27 Usage in the 12.7-13.25 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

2.28 Usage in the 14.5-14.7145 GHz and 15.1365-15.35 GHz Bands . . . . . . . . . . . . . . 72

2.29 Usage in the 17.7-19.7 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

2.30 Usage in the 21.2-23.6 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

2.31 Usage in the 24.2-24.45 and 25.05-25.25 GHz Bands . . . . . . . . . . . . . . . . . . . . 78

2.32 Usage in the 25.525-27.5 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

2.33 Usage in the 27.5-31.3 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

2.34 Usage in the 38.6-40.0 GHz Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

2.35 Other Frequency Bands of Interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

3. COMPARISON OF PREDICTIONS WITH LICENSE DATA . . . . . . . . . . . . . . . . . . . . . 82

3.1 Federal Government Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

3.2 Private Operations Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

3.3 Public Services (Common Carrier) Bands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

3.4 Broadcast Auxiliary Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

3.5 Cable TV Relay Service (CARS) and Private Cable . . . . . . . . . . . . . . . . . . . . . . 86

3.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

4. PREDICTIONS FOR FUTURE USAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.1 Federal Government . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.2 Private Operational Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.3 Common Carrier Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

4.4 Broadcast Auxiliary Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

4.5 CARS and Private Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.6 HDFS and Non-traditional Fixed Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.8 Summary of Predictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

5. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
vi

FIGURES

Figure 1.2-1. Thousands of miles of fiber deployed by LECs, IXCs, and CAPs .............. 4

Figure 1.9-1. Allocation changes in the 1990-2200 MHz bands. . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 2.1-1. Example of a geographical distribution map. . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 2.1-2. Example of a license density statistics graph (5925-6425 MHz band). . . . . . . . . . . 15

Figure 2.1-3. Example of a typical user bandwidth graph (10.7-11.7 GHz band). . . . . . . . . . . . . 16

Figure 2.1-4. Example graph for number of assignments (406.1-420 MHz band). . . . . . . . . . . . 18

Figure 2.2-1.* Density of fixed assignments per square degree in the 406.1-420 MHz band. . . . . 20

Figure 2.2-2.* License density statistics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 2.2-3.* Number of assignments in the 406.1-420 MHz band. . . . . . . . . . . . . . . . . . . . . 21

* The above set of figures are typical of the standard set of figures describing each band.

Figures 2.3-1 to 2.30-3. Standard figures for the bands between 928 MHz and 23.6 GHz . . . . 22-77

Figure 3.1. Total Federal assignments in fixed bands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Figure 3.2. Total private licenses in the bands above 1 GHz (w/o CARS/PC). . . . . . . . . . . . . . . 83

Figure 3.3. Total common carrier licenses in the bands above 1 GHz. . . . . . . . . . . . . . . . . . . . 84

Figure 3.4. Total broadcast auxiliary licences in fixed bands above 1 GHz. . . . . . . . . . . . . . . . 86

Figure 3.5. Total CARS and private cable licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Figure 3-6. Summary of fixed service licenses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
vii

ABBREVIATIONS

ADSL Asymmetric digital subscriber line 

ATC Air traffic control

AMSC American Mobile Satellite Corporation

BAS Broadcast auxiliary service - used by broadcasters to move signals between facilities

BETRS Basic exchange telecommunications radio service (telephone service via fixed radio link)

BSS Broadcast satellite service - high power satellite TV broadcasting (same as DBS)

CAP Competitive access provider - provides telecom services to business and homes 

CARS Cable relay system - a radio service used to bring TV signals to cable systems

CATV Cable TV or (same thing) Community Antenna TV - public distribution of TV via cable 

CLEC Competitive local exchange carrier (competition for the local phone company)

DBS Direct broadcast satellite - high power satellite TV broadcasting

DCTN Defense Commercial Telecommunications Network

DECCO Defense Commercial Communications Office (part of DISA)

DEMS Digital electronic message service

DISA Defense Information Systems Agency

DoA Department of Agriculture

DoD Department of Defense

DoE Department of Energy

DoI Department of Interior

DoJ Department of Justice

DS-1 Industry standard equivalent to 1.5 Mb/s or 24 voice circuits

DS-3 Industry standard equivalent to 45 Mb/s or 28 DS-1

DTV Digital TV - includes various standards, like HDTV and various lower resolutions. 

EMC Electromagnetic compatibility

ENG Electronic news gathering - temporary BAS TV link used for remote news coverage

FCC Federal Communications Commission

FTS 2000 Umbrella contract for Government procurement of commercial telecom services

GaAs Gallium Arsenide - substrate material used for microwave electronics

GMF Government Master File - database containing Government radio assignments

GWCS General wireless communications service

GPS Global Positioning System - satellite system providing accurate position information

HDFS High density fixed service

HDTV High-definition television

ICR Inter-city relay - BAS link carrying TV between and within cities

ILEC Incumbent local exchange carrier

ISDN Integrated services digital network- telephone system with all services carried digitally

ISM Industrial, scientific, medical - a noncommunication service that requires no license 
viii

ABBREVIATIONS (Continued)

ITFS Instructional TV Fixed service - TV used to provide classroom instruction

IXC Inter-exchance carrier - long distance telephone company

LEC Local exchange carrier - the local telephone company

LMDS Local multipoint distribution system - (28 GHz cellular cable)

LMR Land mobile radio 

MAS Multiple address system - a point-to-multipoint system

MDS Multipoint distribution system - an earlier 2-channel version of wireless cable

MDU Multiple dwelling unit - apartments, hotels, condominiums, etc

MMDS Multichannel multipoint distribution system - new 33-channel wireless cable

MMIC Monolithic microwave integrated circuit 

MSO Multiple system operator - a company that operates many cable systems

NG non-Government assignment or license - administered by the FCC

NOI Notice of inquiry

NPRM Notice of proposed rulemaking

NTSC National Television Standards Committee - the technical standards used for analog TV 

PCS Personal communication services - family of cellular-like digital short-range communications

PSN Public switched network - the network encompassing the whole telephone system

OC-1 Industry standard for optical fiber communications, equivalent to a DS-3 or 45 Mb/s

OC-N Industry standard for optical fiber communications, equivalent to N DS-3s or N x 45 Mb/s

QAM Quadrature amplitude modulation - amplitude and phase modulation for digital systems

RBOC Regional Bell operating company - any of the eight regional telephone holding companies

RDTE Research, development, testing, and evaluation

SCADA Supervisory control and data acquisition - monitor/control of pipelines, railroads, etc.

SHL Studio to headend link - CARS link carrying programs from central hub to cable headends

SMA Small master antenna - similar to CATV, but serving one complex (e.g., hotel or condo)

SMR Specialized mobile radio - a commercial (trunked) mobile radio service

SNG Satellite news gathering - relay of local news coverage from remote site via satellite

SONET Synchronous optical network - telecommunications standard for optical fiber systems

STL Studio-to-transmitter link - a link carrying program material from the studio to the transmitter

TDRSS Tracking and data relay satellite system

TIA Telecommunications Industry Association

TSL Transmitter-to-studio link - a link carrying program and/or transmitter status to the studio

TVRO TV receive-only - a satellite terminal whose only function is to receive TV signals

VA Department of Veterans Affairs

VSAT Very small aperture terminal - a low capacity two-way satellite system using small antennas

VTS Vessel Traffic Service - Coast Guard control system for ships in harbor areas
ix

ABBREVIATIONS (Continued)

WCS Wireless communications service - the set of rules applying to the 2.3 GHz band. 

WDM Wavelength division multiplexing - carrying multiple optical carriers on a single fiber 

WLAN Wireless local area network

WLL Wireless local loop (radio replacement of telephone wires leading to a house or business)

xDSL Various versions of DSL (digital subscriber line) providing several Mb/s with telephone lines
x

EXECUTIVE SUMMARY

This report is an update of a 1993 NTIA staff study “A preliminary look at spectrum requirements for the

fixed services.” The 1993 study examined 30 frequency bands used for fixed services, including historical

license data, and market and technology factors that would be expected to cause the use of these bands to

grow or diminish. The fixed service bands are used chiefly to provide point-to-point microwave services,

a market which is arguably dominated to an increasing extent by optical fiber. A major objective of this

report is to provide current information and insight regarding the degree to which the existing fixed service

bands will continue to be needed for their allocated services.

This report discusses each of the 30 bands individually, including several types of service. The common

carrier service (also called public service) furnishes communication services to the public-at-large. Local

and long distance telephone companies are typical examples of common carriers. Private operational

service provides internal communications for the operators of the service. Private services are used to

control gas pipelines and electric powerline networks, to coordinate local government activities, and to tie

together a corporation’s several operating locations. The broadcast auxiliary service is used by broadcasters

to distribute programs within a broadcaster’s operations, e.g., to transfer a TV program between the studio

and a mountaintop transmitter site. Cable TV relay service and private cable relay service are used to

transfer large numbers of TV channels to cable headend sites and large hotel and apartment complexes.

The Federal Government uses fixed services to provide a myriad of defense and non-defense functions in

locations and circumstances where commercial communication services do not satisfy requirements. 

 Common carrier licenses reached a peak of 78,000 licenses in 1988 and have slightly decreased since then

(76,000 licenses in 1997). While optical fiber has replaced many of the long-distance high-capacity

microwave networks, shorter-range microwave systems supporting rapidly expanding cellular and PCS

networks have proliferated. Recently, however, the number of new microwave links has not been keeping

up with the number of new cellular/PCS sites. This indicates less use of microwave to connect cellular/PCS

sites, but it also may indicate that many sites are being connected using frequencies that are not individually

licensed. Many microwave links have moved from the 4 GHz band to the 6 GHz band, because of

difficulty sharing with satellite downlinks in the 4 GHz band. Rapid growth continues in the 10.5 GHz and

18 GHz bands, mainly in support of cellular and PCS sites. Earlier rapid growth in the 2 GHz band has

reversed, as new band allocations will soon require moving these links to another frequency band.

Common carrier licenses increased by 1.1% annually over the last 5 years; they are projected to increase

by 1% per year for the next 5 years.

The number of licenses for private operational services reached a peak of 53,000 in 1994 and have slowly

decreased since then (50,000 licenses in 1997). Users in the 1.9 GHz band were moved to other bands

(mostly the 6.5 GHz and 23 GHz bands) to make room for new PCS systems. Private operational services

(not counting private cable) grew by 0.3% annually over the last 5 years; they are expected to remain

constant at their present levels for the next 5 years.

Broadcast auxiliary service (BAS) licenses have grown steadily and rapidly (10% a year), reaching 8500

licenses in 1997. The switch to digital TV in the next few years may substantially change the way that

broadcasters use BAS, since additional TV channels will be created (increasing the BAS support needed),

but this may also be an opportunity to change many older BAS systems to fiber. In addition, the FCC is

proposing to reallocate the 1990-2110 MHz BAS band, requiring the broadcasters to purchase new

equipment to fit within the channels in the new allocation. All of this creates considerable uncertainty in

the number of BAS licenses that will be used in the near future. BAS licenses grew at an average annual
xi

rate of 9.5% over the past five years; they are expected to grow at a 5% annual rate over the next 5 years.

Cable TV relay services (CARS) and private cable relay services are used to distribute large blocks of TV

channels to cable TV systems or to private networks serving hotels and apartment buildings, respectively.

Although the two services are technically quite similar, they operate under different regulations, which has

led to different patterns of growth. CARS grew rapidly to 123,000 licenses in 1994, but have decreased

slightly since then. Many current CARS licenses are believed to be unused now, since many cable TV

owners have upgraded their cable systems to carry 2-way digital data. The upgrade typically uses two-way

optical fiber to replace many of the old one-way CARS links. The number of CARS licenses in use is

expected to decrease at a 5% annual rate over the next 5 years, though license holders have been reluctant

to return the unused licenses in the past. 

Private cable relay services have grown very rapidly in the last 7 years (from almost nothing to 85,000

licenses), and they are still growing rapidly. Private cable operators, however, are prohibited from owning

wide-area fiber systems, so private cable will remain much more dependent on microwave services. Private

cable microwave licenses are expected to increase at a 10% annual rate for the next several years. Private

cable may stop growing within 5 years, as it faces competition from new wireless services and other

competitors.

The Federal Government uses microwave point-to-point services for control and monitoring of many widearea systems, like air traffic control, gas pipelines and electric power service, for connecting Federal

mobile radio sites, for tactical communications, and for communications within test and training ranges.

Over the past 5 years, the number of fixed Federal frequency assignments has increased about 1% per

year, resulting in 31,000 fixed service assignments in 1997. Federal fixed assignments are expected to

remain constant over the next five years.

Altogether, total U.S. fixed microwave use (industry and government) reached a peak of about 165,000

licenses and assignments in 1996. (This count does not include CARS or private cable service.) It has

decreased very slightly since then. The total count is expected to remain approximately constant over the

next 5 years.

Several other general trends have been observed. There has been a movement away from the lower

frequency bands (below 5 GHz) and into the higher frequency bands (up to 39 GHz). This has been driven

partly by the reallocation of some lower frequency bands (e.g., 2 GHz) for new non-fixed applications,

partly by the recent functional availability of some new higher frequency bands, and partly by the nature

of some new fixed service applications.

There has been a recent trend toward microwave links that do not need to be individually licensed. This

includes Part 15 transmitters operating in several industrial, scientific, and medical (ISM) bands, the 5

GHz unlicensed national information infrastructure (U-NII) bands, and many new bands that are licensed

by geographical area. Since this report has keyed user growth to the number of licenses, the increasing use

of transmitters that are not licensed individually may cause much user growth to be hidden from the datagathering processes used in this report. The addition of unlicensed transmitters to the reported license

counts might convert the present, apparently stagnant, industry growth patterns to a much healthier 2-5%

annual growth rate. However, most of the actual “unlicensed” counts are not available, and therefore

growth estimates based on them are currently mere speculation. One U.S. manufacturer of Part 15 systems

claims 20,000 radios installed. The trend toward unlicensed transmitters is expected to become even

stronger in the future.
xii

Finally, the nature of fixed microwave applications is changing. Whereas past microwave systems were

used to support a system’s widest bandwidth “pipes,” now there are many applications where only optical

fiber can reasonably support the widest bandwidths. Therefore, many microwave applications are shifting

toward “access” applications–the means by which individual users are connected to a local fiber-based

communications infrastructure. This change will greatly increase the number of microwave systems in use

and will move them much closer to the typical users. Possibly some of these systems will even become

sufficiently numerous and inexpensive to be correctly termed “consumer” systems. Whether they are

consumer products or not, many of these systems will not be individually licensed.

In summary, the future growth of the microwave industry and the fixed service frequency bands used by

that industry will be largely dependent on how narrowly one defines “the industry.” Traditional point-topoint microwave applications are barely holding their own and will be expected to slowly diminish in the

future. On the other hand, new “access” applications–especially at higher frequencies–are expected to

require the massive deployment of microwave communication systems in many frequency bands.
 1

The author is with the Institute for Telecommunication Sciences, National Telecommunications and

Information Administration, U.S. Department of Commerce, Boulder, CO 80303

 2R. J. Matheson and F. K. Steele, “A preliminary look at spectrum requirements for the fixed

services,” ITS Staff Study, May 1993.

1

Spectrum Usage for the Fixed Services

Robert J. Matheson1

This study is an update to a 1993 ITS staff study entitled "A preliminary look at spectrum

requirements for the Fixed Services." That study included a description of the services

provided in 30 of the Government and non-Government frequency bands between

406 MHz and 30 GHz known as point-to-point terrestrial microwave bands. Each of the

30 frequency bands were described in terms of the services provided, growth of licenses,

and the geographical distribution of current licenses. The technical, regulatory, and

economic factors affecting each band and the total microwave market were described, as

well as a prediction of the rate of future growth (or decrease) for each band and market

segment. This study adds 6 more years of license information and updates much data on

recent regulatory and market trends. Some of the general technology and market

descriptions have been left out of this update, but earlier predictions are compared to

actual market performance and revised forecasts are made. 

Keywords: fiber optics, fixed radio services, frequency allocation, frequency assignment, future spectrum

requirements, microwave radio, spectrum crowding, spectrum management, telecommunications

1. UPDATE OF RECENT HISTORY IN MICROWAVE USAGE

1.1 Introduction

This publication is intended as an update to a 1993 ITS staff study on the fixed services.2

 About 30

frequency bands having primary allocations to the fixed services are described here, including the current

applications for each band, a geographical distribution of current systems, statistical user information, and

predictions for growth over the next 5 years. These predictions are based on analyses of technology and

market factors and the current regulatory environment; they should not be construed to imply any special

insights into future spectrum management policies. This update includes 6 years of additional user license

information for each of the reported frequency bands; it also includes information on significant recent

changes in the use of the bands. As an update, this report omits much basic unchanged information about

the use of fixed services that was contained in the original staff study. In addition, some of the information

in this report has not been updated, but it remains identical to that contained in the original staff study.

A major function of the 1993 staff study (and of this report) was to predict the future requirements for

fixed service spectrum bands. Several decades ago, the fixed services were seen as the most likely

technology to provide long-range transport of wideband digital, voice, and TV signals. Transcontinental

chains of microwave relay stations were constructed, and a large number of frequency bands were
 3

Cellular/PCS data from CTIA website statistics, January 4, 1999. (view_98datasurvey1.gif at

www.wow-com.com)

2

allocated to the microwave fixed services. Fully half of the allocated spectrum bands were allocated on a

primary basis to the fixed services. Although these allocations were surely justified at that time, there have

been substantial changes in technology and markets since then. Today, optical fiber carries the vast

majority of broadband long-range communications. In addition, other advances in technology have made

practical a greatly expanded set of wireless communication services. These potential new services require

frequency bands in which to operate. An obvious question for spectrum managers is whether the use of

optical fiber has displaced the use of microwave fixed services to the extent that some of the fixed service

bands could be reallocated to some of the new wireless services. This question has already been answered

in the affirmative for the 1.9 GHz and 2.1 GHz fixed service bands, which have recently been reallocated

to PCS and other Emerging Technology services. 

Some major trends have developed in the past several years, including a sudden growth in some fixed

common carrier bands which was fueled by the need to interconnect many new cellular/PCS sites. The

long-haul fixed services continue to face severe competition from optical fiber, to the extent that traditional

high-capacity fixed services are generally not expected to grow. On the other hand, several new microwave

applications for high-density fixed systems and non-licensed fixed services have the potential to grow

rapidly. In addition to reallocating some of the fixed bands near 2 GHz to PCS applications, the Federal

Communications Commission (FCC) has recently modified the allocations of many microwave bands to

allow sharing between private and common carrier users and has provided more narrow-bandwidth

channelization. The Federal Government has transferred several Federal bands (including some fixed

service bands) to the FCC for reallocation to commercial services. These recent trends will be discussed

generally, in addition to specific references in the descriptions of individual frequency bands. 

1.2 Cellular/PCS Growth

As indicated in the original report, many cellular sites have been connected with microwave links. In most

of these cases, microwave was selected over fiber or copper because of the ability to rapidly and

conveniently install microwave vs. the delays and expense associated with cabling between cellular sites.

Table 1.2 shows the number of non-cellular/PCS common carrier licenses, licenses for cellular/PCS

providers, and the number of cellular/PCS sites, according to Cellular Telephone Industry Association

(CTIA) statistics.3

Table 1.2. Cellular/PCS Licenses and Sites

YEAR

 (December)

 Common

 Carrier

 Licenses

Cellular/PCS

number of

Licenses

Cellular/PCS

number of

Sites

 1994 64008 11797 17920

 1995 59011 13521 22663

 1996 59203 14911 30045

 1997 59979 14780 51600
3

About 21,000 cellular/PCS sites were added in 1997, giving a total of nearly 52,000 sites. Several years

ago we believed that 70% of new cellular sites were connected with microwave links in the 2 GHz, 6 GHz,

11 GHz, or 18 GHz bands, requiring new licenses for about two microwave links per site. Assuming the

same 70% using microwaves, 29,400 new licenses (21,000 sites x 2 links/site x 70% of sites) would have

been issued in 1997 to support the additional cellular sites. Moreover, increased traffic within the whole

cellular system would have required an increase in capacity for many of the internal microwave network

links. Similar calculations would imply that about 71,000 microwave links would be needed to support the

total number of 51,000 cellular/PCS telephone sites.

License data for December 1997 shows a total of about 15,000 microwave licenses in use by cellular

companies, out of a total of 75,000 common carrier licenses. Both of these numbers were essentially

unchanged from the previous year. These numbers probably underestimate the number of common carrier

licenses used to support cellular/PCS, since microwave links embedded in the public switched telephone

network (PSTN) or private companies (but used to support cellular systems) were probably not counted

as cellular. Nevertheless, it is clear that the cellular/PCS industry is no longer installing new licensed

microwave links at a rate proportional to the growth of new sites. 

In spite of the 1997 installation of 21,000 additional cellular/PCS sites, there was no net increase in the

number of licensed cellular/PCS-associated microwave links. Therefore, while the number of cellular/PCS

sites will continue to grow, it does not seem to follow that this growth will appreciably increase the number

of licensed microwave links. This major change from earlier cellular/PCS growth trends is caused by

several factors. Many cellular/PCS systems are using non-licensed Part 15 spread spectrum point-to-point

equipment in the 2.4 GHz or 5.8 GHz ISM bands or are using point-to-point services in bands that are

geographically licensed (e.g., the 39 GHz band). Recently developed “pair-gain” technologies allow the

transport of DS1 signals (1.54 Mb/s or 24 voice circuits) over distances of several miles using ordinary

twisted pair copper telephone wires. Such technology will often be adequate to connect many single sites

in urban areas. Broader bandwidths to connect multiple sites are often available (especially in urban areas)

from multiple fiber providers, including LECs, CLECs, cable TV companies, and independent fiber

providers. Finally, microwave is often used only temporarily, until other alternatives (such as those

described above) become available. Thus, even while many new microwave links may be used every year

to establish new sites, other microwave links are being removed equally rapidly from older sites. 

In addition, extensive use of large microwave antennas at new cell sites may cause or exacerbate public

objections to such sites. Whether this public attitude will continue to discourage the use of microwave links

in future systems (e.g., high density fixed service systems, Section 1.5) is unknown. However, it may

cause system planners to use higher frequency fixed service bands (which can use smaller antennas) or

non-microwave alternatives.

1.3 Deployment of Optical Fiber

The deployment of optical fiber continues at a rapid rate. Figure 1.3 summarizes fiber deployment by the

major telecommunication providers [1]. Although the IXCs, LECs, and CAPs are probably the largest

fiber users, there has also been heavy activity by cable TV systems (not shown here), which consumed

34% of fiber purchased in 1996 [2]. Since typical fiber cables contain 20-50 fibers, the actual route

mileage of deployed fiber cable is only 2-5% of the fiber mileage. Fiber still connects buildings in a

relatively small percentage of geographical areas, even within large urban centers, and microwave links

still remain very useful for interconnecting cellular telephone sites and large businesses. 
4

7 12 34 55 82 123 231 396 643

1313 1826 1293 1723 1900 2093 2211 2236 2300 2458 2587

2943

3420

1206

1783

2297

3249

4389

5697

7508

9018

10698

12343

14017

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

0

5000

10000

15000

20000

LECs

IXCs

CAPs

 Figure 1.3. Thousands of miles of fiber deployed by 

 IXCs, LECs, and CAPs (1987-1997).

Figure 1.3 shows substantial growth in the total miles of installed fiber. In addition to the increased amount

of fiber, the capacity of each fiber to carry data is increasing substantially. The typical maximum

modulation rate for commercial fiber systems has increased to 2.4 Gb/s, which is a four-fold increase over

the typical maximum rate 6 years ago. In addition, wavelength division multiplexing (WDM) allows

multiple data streams to be carried on a

single fiber at slightly different optical

carrier frequencies. As many as 32

separate optical data streams can currently be carried on a single fiber in

commercial systems. Experimental

systems have demonstrated total singlefiber capacities of almost 3000 Gb/s.

Finally, the usefulness of increased data

rate and WDM can be augmented by

using newly-available optical amplifiers, which can greatly extend the useful

transmission distance of most optical

fiber systems. 

The long-range, high-capacity systems

that can be built with this new technology are especially applicable to rapidly

growing transoceanic applications. For

example, the TAT-14 cable (scheduled

to begin operation in the year 2000

between the US and Europe) has a total

capacity of 640 Gb/s, which is a 64-fold increase over TAT-13. This unprecedented increase in undersea

fiber capacity should significantly lessen the need for some intercontinental fixed satellite systems.

Many strategies have been explored for greatly extending the reach of fiber throughout metropolitan areas.

Cable TV companies and local telephone companies have experimented with various versions of fiber-tothe-curb (FTTC) and fiber-to-the-home (FTTH) systems. Local telephone companies are installing fiber-tothe-neighborhood systems (connecting central offices with neighborhood pedestals) and may greatly expand

wideband xDSL systems. The widespread deployment of these systems could make wideband access more

easily available, decreasing the number of microwave links needed to support future cellular and PCS

deployments and wideband business access. However, none of the experimental FTTC or FTTH systems

are assured of becoming widely available in the near future. The passage of the 1996 Telecommunications

Act has partially clarified the rules under which cable TV and telephone companies are able to compete

to supply fiber and other services. The resolution of these rules is expected to fuel a new round of

competitive activity with major investments in the wideband fiber telecommunications infrastructure.

1.4 Fiber versus Microwave in Wide Bandwidth Future Applications

The relative bandwidth capacities of fiber and microwaves is changing. When optical fiber was first used

commercially, it was extremely expensive and it had approximately the capacity of a single wideband

microwave channel. A few years ago, the capacity of a single optical fiber had grown to equal the total

capacity of a whole microwave frequency band. Today, a single fiber can carry communications equal to
5

the whole usable radio frequency spectrum. Tomorrow, who knows? The significance of this trend is that

microwaves and fiber are becoming less interchangeable, causing their fundamental communications roles

to change. Whereas microwaves were once the most usable medium for “broadband” communications,

there are now many fiber applications that require far too much bandwidth to be carried by a microwave

link. Particularly in common carrier applications, where the communications of many users are combined

into a single data stream, microwave will often not be able to support the bandwidth requirements. This

will become more apparent as video and broadband Internet traffic increase the bandwidth requirements

of typical users. 

Thus, microwave links are being squeezed out of the high-bandwidth end of communications and out of

certain applications in wider-bandwidth future communications architectures. Where the traditional

telecommunication architectures used microwaves for long-haul and backbone (and wireline for customer

access), new architectures will use fiber for long-haul and backbone–with microwave WLL, coax, and

wireline for access. For example, a microwave link to a small remote community may become too limited

in capacity, even if it were expanded ten-fold. Although microwave links once furnished the broadband

backbone connecting central offices, in the future they will be useful only as a lower-capacity emergency

back-up, useful if a major earthquake simultaneously severs all the fiber ring connections. What alternative

media will be available to meet normal wideband traffic demands in the future, when the route traffic

exceeds the capacity of existing microwave links?

Microwave technology will become increasingly useful for accessing individual users and narrow- and

medium-bandwidth groups of users–replacing wireline or fitting into the bandwidth gap between wireline

and fiber. We should expect to see more microwave applications for WLL, WLANs, and other new shortrange access technologies. Many of these are non-traditional microwave applications, however, and they

may not be as easily recognized as the traditional microwave fixed services of the past. The new

applications will tend to move the microwave industry closer to the individual user and closer to the mass

market. These short-range access markets will be particularly suitable for higher microwave frequency

bands–where the smaller antenna size, greater frequency reuse, and wider available bandwidths provide

major advantages.

1.5 High Density Fixed Systems

The traditional uses of point-to-point microwave have included high capacity “backbone” systems carrying

multiple DS-3s (often using multiple hops to cover the long distances between large cities), “thin-route”

systems (usually SCADA applications where alternative communications are often not available), and

“quick reaction” circuits where microwave can be installed much faster than wireline circuits (e.g.,

interconnection of cellular sites or temporary connections for special events). High density fixed systems

(HDFS) represent a new type of microwave deployment, which will play a major role alongside the three

traditional roles described previously.

HDFS is characterized by a large number of short range, single-hop, microwave links to local hubs.

Typically, the hubs would be interconnected with fiber, the microwave links would carry wideband digital

(DS-1 to DS-3 capacity), and the short range would permit very high frequency reuse. The hubs might use

a point-to-multipoint architecture (omnidirectional hub or segmented hub, directional user site antennas)

or multiple individual point-to-point links terminating at each hub. Such systems would be particularly

suitable for dense urban environments, using microwave bands above 20 GHz. The use of relatively high

frequency bands permits small directional antennas, wide bandwidths, and short reuse distance. The
6

fundamental premise of HDFS systems is that they would provide a cheaper means than optical fiber for

connecting medium-bandwidth customers, for applications where the existing copper twisted-pair is not

adequate. The typical customer might be a business or a home Internet user or a home TV viewer, though

initial implementations would probably concentrate on office buildings, multiple dwelling units, and hotels.

No HDFS systems have been widely deployed yet, though some are beginning to offer initial services in

multiple U.S. cities. Examples of emerging HDFS systems include Teligent’s WLL at 24 GHz, LMDS

at 28 GHz, Winstar’s “wireless fiber” at 39 GHz, and the proposed“stratospheric repeater” near 50 GHz.

It is too soon to predict which, if any, of the proposed HDFS systems will be commercially successful.

Most of them would assume the role of a CLEC, competing with the local phone system, but additionally

supplying broadband Internet access and (possibly) TV/video programming. 

HDFS is a somewhat fuzzy category. For example, two-way MMDS experiments with two-way digital

services might fit into HDFS, except for the much-lower 2.6-GHz MMDS frequency band. Similarly, one

could envision a telephone central office directing a large number of conventional microwave links to

specific large customers fitting the basic HDFS definition. The major reason for defining a specific official

service category of HDFS–as distinguished from “fixed service (FS)–is that FS often shares frequency

bands with satellite-based fixed services (FSS). Because of the very large number of HDFS terminals and

the high cumulative transmitter power, many people believe that it would be impractical to allow sharing

between HDFS and satellite services.

1.6 Unlicensed Spread Spectrum Systems in ISM and U-NII Bands

A number of companies are manufacturing spread spectrum systems that operate under Part 15 rules as

unlicensed point-to-point radios in the 2.4-GHz and 5.8-GHz bands, which are also allocated to Part 18

ISM systems. These systems typically provide up to 1 or 2 T1 channels with 1-watt transmitter power.

Although these unlicensed radios have no coordinated protection against interference, the combination of

high gain directional antennas, spread spectrum modulation, and error correction usually provide adequate

performance. About half of these radios are used to interconnect cellular/PCS sites. Although leakage from

microwave ovens radiates noise across much of the 2.4-MHz band, this can usually be treated as an

increase in background noise and compensated for in the system gain calculations.

These Part 15 radios have essentially created two new point-to-point microwave bands having very rapid

growth. Although no licensing delays or cost apply to these radios, no protection against interference is

implied or coordinated either. One manufacturer suggests that a useful strategy would be to install a 5.8

GHz unlicensed link and begin operation immediately, while simultaneously applying for a license for

operation in the 6-GHz or 6.5-GHz licensed bands. When the 6-GHz license is issued several months later,

the operator has some options. He can install a licensed radio on a permanent basis, perhaps moving the

unlicensed radio to another new site where the cycle will be repeated. Since the licensed and unlicensed

bands are quite close in frequency, no adjustments to the antennas or waveguides will usually be needed

and minimum additional cost will be involved in the change-over. The operator could also choose to

continue operation in the ISM band, with the option of switching to a licensed band if interference ever

becomes a problem.

The use of the ISM bands for high reliability communications is problematic, mainly because there is no

assurance that today’s adequate performance will remain free of interference in the future. In general, one

should expect very substantial growth in unlicensed systems of many types, e.g., cordless phones and
7

WLANs. Eventually there may be too many additional systems to expect interference-free operation in

crowded locations. Or, maybe not. Another problem, from the standpoint of this report, is that the

presence of these unlicensed radios does not show up in any license databases. One U.S. manufacturer

claims 20,000 radios installed worldwide, mostly in the U.S. This single factor would cause a substantial

under-reporting of growth in microwave usage, converting declining or plateaued usage into consistent

growth.

The situation will be similar in the recently allocated “unlicensed national information infrastructure” (UNII) band. This 5-GHz band with 300 MHz total bandwidth is designed especially to support wideband

WLANs, but it also permits use of directional antennas for long range point-to-point services. Unlicensed

systems with DS-3 capacity are available in the 5.8 GHz part of this band. As with other unlicensed

applications, the possible growth of interference in this band due to uncoordinated use is a potential

problem for which no one has sufficient experience to give a convincing answer yet.

1.7 Reallocation and Rechannelization in the 2 GHz Migration Bands

The FCC has reallocated 220 MHz of spectrum near 2 GHz from fixed services to emerging wireless

technologies, especially PCS. A major part of the 1850-1990 MHz band was auctioned for PCS at the

beginning of 1995, with the remainder auctioned by early 1997. The existing fixed private operations users

in the 1850-1990 MHz band will be required to move out of this band, though their cost of relocating to

another band will be reimbursed by the PCS operator. The spectrum changes required by this reallocation

are evident beginning with 1996 license data. The 2110-2150 MHz and 2160-2200 MHz bands are also

earmarked for reallocation, but the details are still under vigorous discussion and no definite date has been

set for an auction or other reallocation procedures. This has given the cellular operators and private users

in the 2110-2150 MHz and 2160-2200 MHz bands an extra year or two of operation and has encouraged

the continued use of these bands to support new cellular telephone sites. The proposed requirement for

satellite system operators to reimburse incumbents may further delay major changes in the use of these

bands.

To ease the migration of microwave users from the reallocated 2 GHz bands to new fixed bands, many of

the fixed bands at higher frequencies have been rechannelized to include narrower channels and reallocated

to permit shared use by both common carrier and private users, as described in an FCC rulemaking

FCC 93-350 [3]. The rechannelization of the bands was desirable, since the private operational users in

the 1850-1990 MHz band and the private and cellular users in the 2110-2150 MHz and 2160-2200 MHz

bands typically used relatively narrower bandwidths. In addition, the common carriers are now building

most of their wideband capacity with optical fiber, and do not require as large a proportion of their

spectrum to be channelized with 20-MHz, 30-MHz, and 40-MHz bandwidths. This gives private users

access to the wider bandwidths available in the original common carrier bands. It also gives common

carriers access to many more narrowband channels than were previously available to them, more efficiently

matching the limited amount of traffic present at cellular/PCS sites.

Although the December 1997 license data used in this report does not yet completely show the effect of

these allocation changes, frequency coordinators note many "cross-band" licenses (i.e., common carriers

requesting licenses in bands that were previously limited to private operation, or vice versa). 

The following bands are intended as migration bands for users displaced from the 2 GHz bands. The

channelization bandwidths permitted in each band are indicated before and after the changes were made.
8

The channels described below represent overlapping alternative channelization plans; therefore, it would

not be possible to simultaneously use all of the channels listed at a single location. 

Using the 5925-6425 MHz band as an example: The notation of "24 pr" in the column headed “0.4 MHz”

and the row headed “Now,” means that there are now 24 pairs of channels (48 channels in all), each

channel having a 0.4 MHz bandwidth. The original channelization for this band is indicated in the “Was”

row to have included only the 8 pairs of 30 MHz channels. Note that the indicated 24 pairs of 10 MHz

channels or 8 pairs of 30 MHz channels would each occupy 480 MHz (out of the 500 MHz available in

the band). Therefore, the 10 MHz and 30 MHz channelizations must overlap in much of the same part of

the band. Some channelizations represent alternative, rather than simultaneous, uses of the frequencies.

a. 3700-4200 MHz band (was common carrier only).

Was: 20 MHz

Now: 20 MHz (no change)

In the 3700-4200 MHz band, terrestrial fixed links have problems sharing with fixed satellite downlinks.

The existing fixed terrestrial links are leaving this band at a rapid rate, and the lack of any new narrowband

channelization suggests that this band is likely to be relatively lightly used by terrestrial fixed systems in

the future.

b. 5925-6425 MHz band (was common carrier only)

 bandwidth (MHz) 0.4 0.8 1.6 1.25* 2.5* 3.75* 5.0* 10* 30*

Was: --- --- --- --- --- --- --- --- 8 pr

Now: 24 pr 12 pr --- 59 pr 29 pr 13 pr 12 pr 24 pr 8 pr 

* These channels are submultiples of 29.65 MHz, instead of the indicated nominal 30 MHz.

c. 6525-6875 MHz band (was private operations only)

 bandwidth (MHz) 0.4 0.8 1.6 1.25 2.5 3.75 5.0 10 30

Was: --- 6 pr 3 pr --- --- --- 15 pr 17 pr ---

Now: 12 pr 6 pr --- 132 pr 66 pr 31 pr 31 pr 17 pr ---

d. 10.55-10.68 GHz band (was private operations and common carrier)

 bandwidth (MHz) 0.4 0.8 1.6 1.25 2.5 3.75 5.0 10 30

Was: --- --- --- 8 pr 20 pr --- 8 pr --- ---

Now: 24 pr 12 pr --- 52 pr 26 pr 11 pr 11 pr --- ---

e. 10.7-11.7 GHz band (was common carrier only)

 bandwidth (MHz) 0.4 0.8 1.6 1.25 2.5 3.75 5.0 10 30 40

Was: --- --- --- --- --- --- --- --- --- 12 pr

Now: --- --- --- 56 pr 28 pr 14 pr 14 pr 50 pr 13 pr 12 pr

Although the old common carrier bands remain distinguished by the availability of wideband channels

(20-MHz, 30-MHz, and 40-MHz bandwidths), it is likely that the fixed microwave bands will gradually

become more homogeneous in patterns of use, being shared equally by private and common carrier users.
 4

The 4940-4990 MHz band has been exchanged by NTIA for the 4635-4660 MHz and 4660-4685

MHz bands under the substitution authority of the President to facilitate the deployment of a new Navy

system.

9

1.8 Release of 255 MHz of Federal Spectrum

Under Title VI of the Omnibus Budget Reconciliation Act of 1993 [4], Congress required the Federal

Government to release at least 200 MHz of spectrum to the FCC, which would reallocate it for commercial

purposes. Under Title III of the Balanced Budget Act of 1997 [5], Congress required the Federal

Government to give up an additional 20 MHz of spectrum; these bands are designated by an ”*” in the

following table. These frequency bands and their corresponding release dates and conditions have been

identified by NTIA and accepted by the FCC [6].

Table 1.1. Frequency Bands Released by NTIA

FREQUENCY BAND RELEASE DATE PREVIOUS USE

 139-140.5 MHz* January 2008 Fixed, mobile

 141.5-143 MHz* January 2008 Fixed, mobile

 216-220 MHz* January 2002 Miscellaneous

 1385-1390 MHz* Completed Fixed, radar, mobile

 1390-1400 MHz Completed Fixed, radar, mobile

 1427-1432 MHz Completed Fixed, mobile

 1432-1435 MHz* Completed Fixed, mobile

 1670-1675 MHz Completed Radiosondes, met sat

 1710-1755 MHz January 2004 Fixed, mobile

 2300-2310 MHz Completed Radar, mobile

 2385-2390 MHz* January 2005 Radar, mobile, tm

 2390-2400 MHz Completed Radar, mobile

 2400-2402 MHz Completed ISM, radar, mobile

 2402-2417 MHz Completed ISM, radar, mobile

 2417-2450 MHz Completed ISM, radar, mobile

 3650-3700 MHz Completed Radar

 4635-4660 MHz4 Completed Fixed, mobile

 4660-4685 MHz2 Completed Fixed, mobile
10

Figure 1.9-1. Allocation changes at 1990-2200 MHz

It is significant that the largest segments reallocated include bands used by the Government primarily for

fixed services, especially the 1710-1755 MHz and the 4940-4990 MHz bands. These recent reallocations

are mentioned in the respective sections of the report. 

1.9 Allocation of 2 GHz Spectrum for Mobile Satellite Service (MSS)

Although Section 1.7 discussed the creation of the PCS bands from the 1850-1990 MHz fixed service

band, the Emerging Technologies allocation also identified the 2110-2150 MHz and 2160-2200 MHz bands

with common carrier (CC) and private (PRI) allocations for future reallocation to new services, including

mobile satellite services (MSS). The matter has not yet been fully decided, but the proposed changes as

of November 1998 [7] are summarized in Figure 1.9-1.

These changes include the following major features. Two paired MSS bands were created–an uplink band

at 1990-2025 MHz and a downlink band at 2165-2200 MHz. The broadcast auxiliary service (BAS) band

originally at 1990-2110 MHz was reduced and moved to 2025-2110 MHz. A new general-purpose fixed

and mobile band was created at 2110-2150 MHz, with the intention of auctioning the band and allowing

the auction winners to decide the details of its use. The MDS frequencies at 2150-2160 MHz or 2150-2162

MHz remain unchanged.

As with the earlier Emerging

Technologies allocations, it is intended

that licenses in the general-purpose fixed

and mobile band will be auctioned. The

winners of these licenses and the MSS

licenses will have the option of designing

new systems that do not interfere with the

existing fixed users, or paying the costs

of moving the existing users to new frequency bands. Many of the details are not

yet decided, but some of the problems

include: 

1. Almost all existing users will need to be moved before any service can begin. Because of the global

nature of MSS systems, presumably many existing users will need to be moved before service can start.

This contrasts with the earlier Emerging Technologies moves, where the incumbent users could be moved

one geographical area at a time by the new licensee who would pay to move those particular incumbents

in that particular geographical area. Moreover, previous PCS licenses could concentrate on moving users

out of a few urban areas, gaining large numbers of potential customers with relatively small displacements

of existing users. The MSS customers are (almost by definition) spread throughout the countryside, i.e.,

wherever there is insufficient traffic demand to build a cellular/PCS system. Thus, MSS requires larger

areas to be cleared of incumbent users before new services can be offered to a substantial number of

customers.

2. The existing 120 MHz-wide BAS band will be squeezed into a new 85 MHz-wide BAS band. This move

depends on reducing the BAS channelization bandwidth from about 17 MHz to only 12 MHz, which may

require all of the old 17-MHz analog equipment used for TV electronic news gathering (ENG) to be

replaced by new 12-MHz equipment using digital compression. The lack of compatibility between the old
11

and new equipment and channelizations may make it difficult to replace old equipment piecemeal, possibly

requiring a single coordinated switchover date. 

2. SUMMARY OF CURRENT BAND-BY-BAND USE

This section summarizes the usage in about 30 frequency bands having a primary allocation to the

Government or non-Government fixed services. The bands are arranged in ascending frequency order, and

each section follows the same general pattern of presentation. Information on the allocations for each band

and a description of the significant uses for the band are presented. Numerical information is presented

for each band, including the geographical distribution of assignments and a recent history of the number

of licenses. The technological, regulatory, and market factors that affect the use of the bands are described.

Finally, a prediction is made for the future growth (or decrease) in the number of assignments in the band

in the next 5 years.

The emphasis in this report is on fixed services, not on individual frequency bands. Therefore, the

following band summaries put more emphasis on a description of the fixed services in a given band and

less emphasis on cataloging all of the non-fixed services which may share a particular frequency band. This

usually causes no problems in understanding the fixed service use in non-Government bands, where each

band is used according to a channelization plan and contains systems that are highly homogeneous in their

characteristics. There are some non-Government bands (e.g., the 4-GHz common carrier band) where

extensive sharing with dissimilar systems (e.g., satellite downlinks) limits the use of fixed systems; we

have specifically mentioned the non-fixed services in these cases. 

The problem of sharing with non-fixed systems is often more complicated in the Government bands.

Government bands are often less homogeneous and follow channelization schemes to a less rigorous

degree. The 1710-1850 MHz band, for example, contains not only a wide variety of terrestrial point-topoint links, but also mobile radio, aeronautical mobile links (including wideband video and telemetry),

satellite links, and some classified systems. In the 1710-1850 band, the additional services represent a

minority of the total number of assignments, but they substantially constrain use of the band for fixed

systems. Because of the wide variation of system characteristics and rapid changes in system deployment,

the constraints may not be easy to describe, except on an individual basis for each type of system. That

level of detail is beyond what was intended for this document.

2.1 Methodology and Approach

The number of assignments/licenses in each band was obtained from one of three sources, depending on

the frequency band. Note that NTIA uses the term "assignment" to mean the same as an FCC "license;"

we will use the terms interchangeably in this report. The Government Master File (GMF) from NTIA was

processed to obtain data on the Federal frequency bands. Data files from Comsearch (Reston, VA) were

used to describe use in most of the non-Federal frequency bands. For some shared bands (i.e., shared

between Federal and non-Federal users), we used GMF data for Federal use and Comsearch data for nonFederal use. For MDS and MMDS bands, we used license data that we had obtained earlier (December

1993) from Dataworld, Inc. (Bethesda, MD). 
12

Data for each band includes four basic sets of numerical information:

1. the current geographical distribution of fixed assignments (July or September 1998),

2. a statistical distribution of fixed assignment geographical densities (July or September 1998),

3. a statistical distribution of channelization bandwidths (July or September 1998), and

4. a historical trend summary of the total number of assignments at the end of the 11 years.

For most services, only the transmitters were counted. In some bands with TV receive-only (TVRO)

terminals, we also present information on receivers, because their presence greatly affects the use of the

bands. A typical point-to-point two-way microwave link will count as two items, one count for the

transmitter on each end. If a particular link bandwidth needs to be expanded–for example–from 2.5 MHz

to 5.0 MHz, this process might or might not result in a larger number of licenses counted. If the expansion

were accomplished by adding a license for an additional 2.5-MHz channel, this would increase the count.

If the 2.5-MHz channel were changed to a 5-MHz channel, the license count would not change on a long

term basis. During the transition from 2.5 MHz to 5 MHz, however, both (old and new) licenses might

be counted; the old 2.5-MHz channel license would be deleted after the 5-MHz channel was installed. 

2.1.1 Geographical and Statistical Data

The geographical and the statistical presentations were obtained from the most recent data sets that were

available. The information on current Government band assignments was developed from the September

1998 GMF, usually selecting only fixed assignments. For this study, Government station classes of FX,

FXD, FXE, and FXH were considered fixed services. Although many Government bands also contain

significant numbers of non-fixed assignments, this study focuses on the fixed services. Current nonGovernment license data was developed from the July 31, 1998 Comsearch files. For MDS and MMDS

bands, we used license data that was obtained earlier in December 1993 from Dataworld, Inc. (Bethesda,

MD). When possible and significant, we divided the assignments into separate user categories, since this

may make trend information easier to understand. Geographical and statistical data are not necessarily

commensurate and comparable between different bands and services. The nature of some services makes

them difficult to compare with other services. Nevertheless, all bands were treated in as similar a manner

as possible. The Government assignment count usually includes classified assignments, but generally does

not show the number of pieces of equipment each assignment represents. For example, the entire inventory

of the (fictitious) ABC-123 transportable microwave terminals will often be represented by a few

assignments (e.g., one assignment for each facility using that equipment). However, any ABC-123 terminal

permanently installed at a particular site would typically have an individual assignment for each

permanently installed transmitter. Many of the details of exactly how assignments were treated were not

recoverable from the pre-1991 archival file summaries that we used to get the Government historical

information. Similarly, we did not ask for Comsearch data to break out cellular users before 1994.

2.1.2 Geographical Maps

Each frequency band is described with a map showing the geographical distributions of fixed assignments

in the United States. An example of a geographical map is shown in Figure 2.1-1. The geographical area

of the United States was covered by a grid with 1-degree resolution in latitude and longitude, creating

about a thousand 1-degree by 1-degree blocks. Circles of various sizes were placed at the center of each

of these blocks; the size of the circle indicates the total number of transmitters in that block. The absence

of any circle shows that no transmitters were present in that block. These maps show usage patterns that

help to understand how the bands are used on a geographical basis–e.g., whether the band is used mainly
13

6525-6875 MHz

Transmitters per 1 Degree Block

1

2 to 19

20 to 59

60 to 199

200 or More

Figure 2.1-1. Example of a geographical distribution map.

in rural or urban areas. This information might be useful in possibly suggesting services that might be

particularly amenable to sharing on a geographic basis. Note that these maps show only the fixed services;

the absence of fixed assignments does not imply an absence of other types of assignments.

This geographical mapping is intended to show relative usage in a single band between various

geographical areas in the United States, rather than the difference in crowding between the various

frequency bands. Therefore, the values representing the number of transmitters in each block have been

scaled according to the number of transmitters in the band. This means that the map of a lightly used band

might have the same appearance as the map of a heavily used band. The scales on these maps should be

checked before using these maps to compare the usage between several frequency bands. The scales used

in these maps match the scales used in the 1993 staff study (chosen as described above), which was done

to facilitate a comparison of the maps to identify areas of change. Therefore, in many cases a “blacker”

map may indicate growth and a “lighter” map may indicate shrinkage, rather than being crowded or

sparse.

Finally, note that the maps show only the number of licenses within a block, without reference to the

bandwidths associated with these transmitters. It is possible that some geographical areas using fewer

transmitters with wider bandwidths may actually be more crowded (from a spectrum usage standpoint) than

an area using a larger number of narrowband channels. (See discussions on bandwidth in Section 2.1.5.)

2.1.3 Statistical Tables

The statistical tables for each band contain a summary of some of the more important statistical information

for the band, illustrated by the example in Table 2.1.

1. Total US (fixed) assignments. This is the total number of U.S. fixed assignments/licenses in that band,

as enumerated in the July 1998 Comsearch database or the September 1998 GMF database. The first five

rows in the table all were derived from these databases. In the case of the Federal bands, the data is for

fixed assignments only.
14

 total US assignments 6174

 maximum assignment density 64

 effective number of channels 23.4

 average U.S. channel reuse 264

 peak reuse/1-degree block 2.7

 annual growth (last 4 yr) 26%

 est. annual growth (next 5 yr) 20%

 Table 2.1. Example of Table of Statistics for

 the 944-952 MHz Band

2. Maximum assignment density. This is the

highest number of assignments found in any 1-

degree by 1-degree block in the United States.

This number was obtained from the data used to

plot the geographical map for each band. It is

equal to the largest density value in the license

density statistics graph (Section 2.1.4).

3. Effective number of channels. This number

represents the effective number of channels in

the band, based on the channel bandwidth

statistics from user licenses. It is used only to

calculate the channel re-use numbers. For a

band that is divided into a single set of equal

bandwidth channels, this number is simply the

total number of channels in the band. When the

band can be divided into channels of different

bandwidths, or when channels are customarily assigned by combining a number of narrowband channels

to obtain the required bandwidth for a particular system, the effective number of channels is not so easy

to determine. For these cases, this number is computed by dividing the total bandwidth in the band by the

average channelization bandwidth (see Section 2.1.5 for details on average channelization bandwidth). For

most Government bands, the effective number of channels was found by dividing the total bandwidth by

the average user bandwidth.

Note that many of the private and common carrier bands have been rechannelized since the 1993 staff

study, adding narrower channelizations suitable for relatively narrowband SCADA, cellular, and PCS

applications (matching the application bandwidths needed by many users migrating from the 2-GHz

Emerging Technology bands).

4. Average U.S. channel re-use. This field shows, on the average, how many times a typical channel was

re-used over the entire United States during July or September 1998. It is obtained by dividing the total

number of U.S. licenses (item 1) by the effective number of channels in a band (item 3, described in the

preceding paragraphs). This factor is useful for comparing “crowding” between bands, though many other

operational and technical factors may modify this simple comparison. 

5. Peak re-use/1-degree block. This field shows the number of times that an average channel was re-used

within the single 1-degree geographical block with the highest number of assignments. This shows how

often a given channel was re-used within the most heavily crowded conditions. It was obtained by dividing

the peak number of licenses in a 1-degree block (item 2) by the effective number of channels (item 3).

This data may be misleading for frequency bands that have multiple channel bandwidths. Specifically, the

calculation of this number assumes that the distribution of channel bandwidths in the “peak re-use” block

is the same as it is in the United States as a whole. Moreover, the most-crowded block is selected by

considering only the number of licenses, without regard for the bandwidths associated with those licenses.

Nevertheless, peak re-use data attempts to describe the actual areas of the worst spectrum crowding in the

U.S. on a band-by-band basis. This number is useful for comparing worst-case crowding between bands,

though many other operational and technical factors may modify this simple comparison. This data might
15

Figure 2.1-2. Example of a license density statistics

 graph (5925-6425 MHz band).

also be used to infer that the practical upper limit for band usage must be at least as large as this number,

as well as to suggest which frequency bands may be near that limit.

6. Annual growth rate (last 5 years). This field was calculated from the 11-year chart of annual licence

data (Figure 2.1-4) to give the compounded annual growth rate which would have been needed to change

the number of 1992 licenses to the number of licenses in 1997. Note that this historical data comes from

data sets that were current at the end of each nominal calendar year, which is a different set of data than

was used for the immediately preceding five items. (See further details in Section 2.1.7.) This data and

the underlying causes are described more fully in the historical trends paragraph. In some cases, a different

starting date was selected to more accurately describe the growth mechanisms that are believed to be

currently active and expected to affect future growth.

7. Estimated annual growth (next 5 years). This is the annual percentage change for (compounded)

growth that would be required to convert 1997 license numbers to the expected license numbers five years

from now. It is described more fully in Section 2.1.9.

2.1.4 License Density Statistics Graph

The license density statistics graph (Figure 2.1-2) is

based on the same information found in the

geographical map, but the graph organizes this data as

a cumulative statistical distribution. This distribution

shows what percentage of the 1-degree blocks contains

a total number of licenses equal to or greater than the

density shown on the ordinate. The example graph

uses data from the 5925-6425 MHz band (not shown

in Section 2.20). 

The graph shows the degree to which licenses are

uniformly distributed on a geographical basis. If all 1-

degree blocks had the same density of transmitters, the

graph would approximate a horizontal line at the level

of the density. The example graph shows that the

highest density of transmitters was about 340

assignments in a 1-degree block (which agrees with the

“peak assignment/1-degree block” entry of “338" in

Table 2.20-1), that about 1% of the blocks have at least 200 assignments or licenses, and that 10% of the

blocks have at least 80 licenses. 

For the purposes of this calculation, it was determined that the United States included 951 1-degree by 1-

degree blocks. Therefore, the highest number of licenses in a single 1-degree block is plotted at the 0.1

percent position (the left margin of the graph). The count of 951 blocks includes some non-land coastal

areas immediately adjacent to the United States (especially in the Gulf of Mexico, where substantial

numbers of transmitters provide service to petroleum production facilities). It also counts any 1-degree

block that touches the U.S. border, if that block also contains at least one U.S.-licensed radio in any

frequency band included in the study.
16

Figure 2.1-3. Example of a typical user bandwidth

 graph (10.7-11.7 GHz band).

For most frequency bands, the license density statistics graph or the user bandwidth chart (but not both)

was included in the 2-page summary section. The selection was usually based on what information was

available or which graph provided the most useful information.

2.1.5. User Bandwidth Graph

As part of the relocation of fixed systems from the 2 GHz bands (which contained large numbers of narrow

bandwidth channels), the FCC added narrowband channelizations to most of the migration destination

bands. As a consequence, many fixed bands now have channels that vary over a wide range of

bandwidths–e.g., a 75:1 range in the 6 GHz band. Therefore, when analyzing potential band-crowding

conditions, it is now important to consider the bandwidth of licensed channels as well as the total number

of licenses. For example, in the case of the 6 GHz band, as much as a 75-times increase in the number of

licenses might not represent any actual increase in spectrum usage, if all of the new population of licenses

were for the narrowest-bandwidth channelizations. Furthermore, a knowledge of channel bandwidths

provides important information about the ways that the channels are being used by various industries, and

this information may be useful in forecasting trends about those industries. 

Figure 2.1-3 shows a typical bandwidth distribution

graph. The number of channels licensed for various

bandwidths is shown for several groups of users. In most

cases, the licensed bandwidth was obtained by examining

the channel group designator for each license (since each

channel group has a specific channel bandwidth). In a

few cases, it was necessary to infer the bandwidth from

the emission designator information. Finally, in a small

number of cases, it was necessary to guess at the

bandwidth by examining the application.

This procedure often resulted in a large number of

bandwidths, including some that did not correspond to the

nominal channelization bandwidths available in a

particular band. These bandwidths were combined into

convenient groups and plotted on the bar graph according

to the following rule: Each bar is labeled with the highest bandwidth included in the count, and it contains

all bandwidths down to the limit of the next lower bar. In the 10.7-11.7 GHz band shown in the example

graph, there are channelizations that provide for bandwidths ranging between 1.25 MHz and 40 MHz.

However, the graph does not actually show each of the channelization bandwidths for each of the user

groups. Instead, the graph shows only selected combinations of user groups and bandwidths. This selection

was necessary because numbers in some categories were either much larger or much smaller than others,

as well as the presence of various intermediate bandwidths.

The following rules were used in placing licenses into various bandwidth categories. The bar with the

lowest bandwidth contains all licenses with bandwidths less than or equal to the labeled bandwidth.

Therefore, in this chart, the “5 MHz” bar includes all licenses with bandwidths of 5 MHz or less,

including 1.25-MHz, 2.5-MHz, 3.75-MHz, and 5-MHz channelizations, as well as any miscellaneous

bandwidths within this range of bandwidths. The remainder of the bars contain licenses with bandwidths

less than or equal to the labeled bandwidth, but greater than the labeled bandwidth for the next lower bar.

Therefore, the “10 MHz” bar contains the count for all licenses with bandwidths greater than 5 MHz, but

less than or equal to 10 MHz. Finally, the reader should note the statement immediately above the graph
17

that says“9008 Com Carrier 40-MHz licenses omitted.” In this band, 40-MHz bandwidth common carriers

account for the great majority of licenses in the band, but including this category within the graph would

require changing the scale on the graph to the extent that the other categories would be almost invisible.

Therefore, the 9008 common carrier licenses with 40-MHz bandwidths were omitted from the graph, but

included in the statement above the graph.

The data from the bandwidth chart were also used to calculate the average bandwidth for the band. The

averages were calculated by summing the channel bandwidths of all licenses and dividing by the number

of licenses. As described earlier, most of the bandwidths used in this calculation are the nominal channel

bandwidths, instead of the bandwidth of the actual emission in the channel. Since a user will typically need

to select a channelization bandwidth that is at least as large as the intended emission, channel bandwidths

may be somewhat larger than the actual emission bandwidths. The degree to which these bandwidths may

be inflated by requesting bandwidths sized for larger anticipated future requirements is not known.

In the Federal GMF records, the most easily accessible bandwidth is contained in the emission designator.

This bandwidth is equal to the actual emission bandwidth, instead of the nominal channelization bandwidth.

Therefore, the values of listed Federal bandwidths are considerably smaller than bandwidths from nonFederal bands. In most cases, the average Federal bandwidths were adjusted upward to match comparable

channelization bandwidths that would have been calculated for non-Federal licenses. For example, in the

406-420 MHz Federal band, most radios are assigned in 25-kHz channels, but the emission designator is

“16F3"—which denotes a 16 kHz emission bandwidth. For purposes of this paper, 16F3 was counted as

25 kHz. Partly because of these difficulties, no bandwidth graphs were included for Federal bands.

The average bandwidth for all users in a band is used to calculate the effective average number of channels

in a band (see Section 2.1.3, describing the Statistics table). Specifically, the average number of channels

is calculated by dividing the total bandwidth in the entire band by the average bandwidth of users. This

often gives an average number of channels that is not necessarily an integer.

The average number of channels is used to calculate the average number of times that a given part of the

spectrum in a band is reused within the United States (average US channel reuse), and the number of times

that a given frequency is reused within the most crowded 1-degree x 1-degree geographical area (peak

reuse 1-degree block). The “US-average” data is accurate; the “peak reuse” data may not be accurate. The

problem with the “peak reuse” data is that the calculations assume that the distribution of channel

bandwidths is the same for the most crowded area as it is for the whole US average. In fact, the mostcrowded area was selected by merely counting the number of licenses within the area, without regard for

the channel bandwidths associated with those licenses. It is theoretically possible that the area with the most

licenses is composed mostly of licenses for narrower channels, and that it is less crowded than an area

having fewer total licenses (but more licenses for wider bandwidth channels). However, although the mostcrowded-area calculations may be incorrect (strictly speaking), they are still believed to provide useful

insights, and the strictly correct calculations would have required much more detailed data and more

elaborate calculations.

Finally, it should be noted that the bandwidth distribution graph was not included for several bands.

Bandwidth graphs were omitted when bandwidth data was unavailable or when the bandwidth data was

uninteresting (e.g., when there was only one channelization bandwidth). 
18

Figure 2.1-4. Example graph for number of

 assignments (406.1-420 MHz band).

2.1.6 Typical Users

This information describes the current set of typical applications found in a band, along with other

information that may help the reader understand how a band is being used. In some cases, we have given

independent assignment counts for different types of users. This information came from various

sources—often from different sources than were used for the geographical and statistical data or the trend

data. We note that totals often do not match exactly between the sources, but we believe that this

information is still useful to give an approximate indication of the numbers of different users. Most of the

information on the number of agency assignments in Government and shared bands came from the

September 1998 GMF. Average bandwidth data reported in this section was computed from 1998 data.

2.1.7 Recent Trends in Number of Assignments

Figure 2.1-4 shows historical license trend information for the 1987-1997 period for the 406.1-420 MHz

band. The bars represent end-of-year data, either from the last months of the respective year or from early

months of the following year, depending on what was available. The Comsearch data was taken from files

archived on December 31 of each year. The GMF data before 1992 was taken from the initial part (usually

January) of the following year. Therefore, a bar that is labeled "1990" would contain December 1990

numbers if it is describing a non-Federal band (Comsearch data), but January 1991 data if it is describing

a Federal band (GMF data). Beginning in 1992, we had more ability to select GMF data. The Federal data

from 1992-1997 were derived from December 1992-1997 GMF databases, respectively.

In many of these graphs, the users are divided into particular groups so that different trends can be

distinguished and attached to individual user groups. The example graph contains two sets of users:

“mobile, etc.” and “fixed only”. The shaded

“mobile, etc.” bars contain either a mixture

of user types (1990 and earlier, when no

division between user groups had been made)

or mobile and other non-fixed users (after

1991). The striped “fixed only” bars contain

only fixed users, wherever these bars exist in

the graph. Similar divisions will be made on

other graphs. 

It should be noted that the GMF records allow

multiple station classes to be associated with

a single assignment. An assignment was

counted as “fixed” if any of its associated

station classes were in the fixed category.

The pre-1992 archived Government data

could not easily be sorted for the assigned

service; it was necessary to use the total

number of assignments in a band, combining all types of users. The average growth rate (last 5 years) was

obtained from the 1992 and 1997 data. The calculated growth rate is the compounded annual rate (constant)

that predicts the net growth from 1992 to 1997. In some cases, where obvious changes of slope had

occurred more recently than five years ago, we adjusted the calculations to use a different starting year and

corresponding term of growth. 
19

The historical data is useful to show which bands are becoming more or less crowded. This information

is based completely on frequency assignment counts, however, and it does not necessarily show whether

the indicated assignments are actually being used or being implemented with wider or narrower

bandwidths. In many bands, there is no mechanism to ensure that users turn in their frequency assignments

when they are finished using them. Particularly in a frequency band whose use has been decreasing, the

assignment database information may lag behind the actual usage. The database manager may learn of the

departure of the equipment only when the user fails to renew an assignment when it expires several years

later. In addition, we understand that some point-to-point common carriers have been instructed to

terminate licenses at a given site only when the last transmitter in a band ceases operation. Similarly, in

bands where there is a lot of activity associated with relocation and re-use of transmitters, apparent growth

may be caused by the requirement to obtain a new license each time a transmitter is relocated or when its

ownership is changed. The corresponding mechanism for deleting the old license is not necessarily as

certain or swift, which could cause license data to become inflated with obsolete licenses. The degree to

which this effect causes a significant distortion of usage trends is unclear at this time. 

2.1.8 Comments

The “Comments” section contains any additional information that may be helpful in understanding the

current or future use in a band, including general market trends, technology factors, or regulatory actions

that are expected to significantly affect future use of the band.

2.1.9 Estimated Future Growth Rate 

This section indicates the predicted annual percentage growth, averaged over the next 5 years. The growth

rate derived in this section is also included in the table of statistics for the band, described as part of Table

2.1. In some bands, we expect that the growth rate will change substantially over the next 5 years, so that

the present growth rate will be considerably different from the predicted average growth rate. The growth

rate was calculated by estimating the number of assignments at the end of the year 2002 and calculating

the average annually compounded growth rate needed to achieve that number. If the number of assignments

is expected to decrease, the growth rate is expressed as a negative number. For example, a -5% growth

rate would mean that each successive annual assignment count contained 95% of the assignments counted

in the previous year. A narrative description of the factors that were included in that prediction are found

in each band description in the paragraph on "estimated future growth rate."

It should be noted that the estimated growth rate for each band is based on a large number of technological,

regulatory, and economic factors, each of which may be subject to uncertainty and possible errors. The

regulatory environment is a particularly important factor, and it is one that may be changing rapidly. It is

particularly difficult to estimate future growth in bands where the allocations are scheduled to change soon,

but where no detailed rules have been established yet for the proposed new services. In certain cases there

may be a surplus of spectrum for new services, and actual use of the band may be pushed mainly by

regulatory requirements for rapid build-out.
20

406.1-420 MHz

Transmitters per 1 Degree Block

1

2 to 5

6 to 19

20 to 59

60 or More

Figure 2.2-1. Density of fixed assignments per square degree in the 406.1-420 MHz band.

Figure 2.2-2. Assignment density statistics.

2.2 Usage in the 406.1-420 MHz Band

Government Service

Typical users. The 406.1-410 MHz band is shared by Government and non-Government users. Primary

allocations for the Government are the fixed, mobile, and radio astronomy services, while non-Government

has only radio astronomy allocations. The 410-420 MHz part is exclusive to the Government and the

allocations are to fixed and mobile services. Geographical and statistical assignment distributions are shown

in Figures 2.2-1 and 2.2-2 and Table 2.2-1.

Table 2.2-1. Statistics for Fixed Assignments Only

 in the 406.1-420 MHz Band

 total U.S. fixed assignments 10,724

 maximum assignment density 185

 effective number of channels 556

 average US channel reuse 19.3

 peak reuse/1-degree block 0.33 

 annual growth rate (last 6 yr) 0.0%

 est. annual growth (next 5 yr) 0.0%

This band is shared between land mobile radio (LMR)

and fixed services. It was recently rechannelized to

12.5-kHz channels, though most equipment is still 25-kHz FM voice, and 25 kHz was used as the average

bandwidth in the frequency reuse calculations. The band is primarily allocated for nonmilitary users,

though military agencies can use it for non-tactical traffic. This band is the Government general-purpose

UHF band, with a wide range of mobile and fixed communication systems. Typical fixed uses include links
21

 Figure 2.2-3. Number of assignments in the

 406.1-420 MHz band.

to connect nodes of LMR networks (more than 5,000 fixed assignments belonging mostly to the

Departments of Agriculture, Energy, Interior, Justice, and Veterans Affairs (VA), and Tennessee Valley

Authority (TVA)), as well as links for narrowband weather, hydrology, or seismic sensors. 

Civilian Government agencies have over 70% of the fixed assignments in the band, and the Departments

of Agriculture, Commerce, Interior, and Justice, and the FAA each have about 1400 fixed assignments.

The Department of Energy has about 810 fixed assignments used for telecommand, law enforcement,

administrative purposes, trunking and seismic telemetry. Commerce, FAA, Treasury and Interior typically

use fixed assignments for law enforcement and protection of Government personnel, connection of mobile

radio base stations, flood and wind-shear warning, administration, and for supervisory control and data

acquisition (SCADA) for electric power transmission nets. The Air Force, Army, Navy, and Coast Guard

have about 360, 880, 320, and 230 fixed assignments, respectively. These assignments are used for

administration, maintenance, trunking, paging and range control, disaster preparedness, training, shipboard

operations, and security.

Recent trends in number of assignments.

Growth in this band over the past 11 years

is shown in Figure 2.2-3. The consistent

growth reflects the increasing use of LMR

to provide Government services. A 1987

study showed that in 1986 there were about

12,500 assignments in the 406.1-420 MHz

band, of which 7,736 or about 62% were to

the fixed services (Nebbia, [8]). At the end

of 1997, there were 25,706 assignments in

the band, of which 10,384 or about 40%

were to the fixed services. Although the

total assignments over the 1991-1997

period increased by about 30%, the number

of fixed assignments remained

approximately unchanged, thus indicating a

compounded growth rate of 8.6%/year for

mobile services and zero growth for fixed

services. 

Comments. This band is changing from a

predominately fixed band to a predominately mobile band. This band has seen strong growth in trunked mobile radio systems, especially on major

military bases and test ranges. Trunked systems are often shared between multiple Federal agencies and

often support many users per channel. Thus, the number of mobile users is growing faster than the number

of assignments. The average bandwidth of mobile users will decrease as existing 25-kHz users are

converted to 12.5-kHz channelization.

Estimated future growth rate. The fixed service assignments in this band are expected to remain

approximately constant over the next 5 years, while the number of mobile assignments are expected to

continue to grow at 8% per year. Future growth (especially mobile) may be greatly influenced by the

implementation of the proposed Public Safety Wireless Network (PSWN), a joint nationwide Justice and

Treasury program to facilitate development of shared mobile networks. 
22

928-929 & 952-953 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.3-1. Density of licenses in the 928-929 MHz and 952-953 MHz bands.

Figure 2.3-2. License density statistics.

2.3 Usage in the 928-929 MHz and 952-952.85 MHz Bands

 MAS Private Operational and Public Services

Typical users. This pair of bands is allocated for Multiple Address Service (MAS), using 80 pairs of 12.5-

kHz channels, which can also be used as 40 pairs of 25-kHz channels. Various parts of the band are

allocated to general users (28 pairs of 12.5-kHz channels), electrical utility users (40 pairs of 12.5-kHz

channels, opened up recently to other users), and public mobile users (12 pairs of 12.5-kHz channels).

These stations are used in a master-interrogator/remote-reply mode of operation, with 928-929 MHz used

for remote stations and 952-953 MHz used for master stations. At least four remote stations must be used

with each master to qualify for this type of service, though our license data does not include any counts

of remote stations. MAS is a relatively new service, with many innovative uses being developed, including

SCADA and meter-reading for utilities, alarm systems (fire, burglar, intrusions), and point-of-sale

applications (credit card verifications). Geographical and statistical assignment information are shown in

Figures 2.3-1 and 2.3-2 and Table 2.3-1.

 Table 2.3-1. Statistics for the 928-929 MHz

 and 952-953 MHz Bands

 total US assignments 7835

maximum assignment density 99

 effective number of channels 62.5

 average US channel re-use 125

 peak re-use/1-degree block 1.6

 annual growth rate (last 5 yr) 11.8%

 est. annual growth (next 5 yr) 10%
23

Figure 2.3-3. Number of licenses in the 928-929 MHz

 and 952-953 MHz bands.

Figure 2.3-4. 900-MHz MAS bands.

These bands are also allocated via footnote to Government offshore radiolocation systems, which can

operate on a not-to-interfere basis.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.3-3. The lower bar shows the number

of MAS systems in the 952-953 MHz

band. The corresponding paired remote

stations in the 928-929 MHz band are

not included in the counts. The upper

bar shows the number of one-way (simplex) stations licensed in the 928-929

MHz Band. 

Comments. The allocation of this band

is being re-examined in an FCC NPRM

(WT Docket 97-81, released 02/27/97).

This NPRM states that these licenses are

used mostly for private (internal) use

and proposes to reserve the 928-928.85

MHz/952-952.85 MHz and the one-way

956.25-956.45 MHz bands (Section 2.6)

solely for private use. 

Estimated future growth rate. The

present annual growth rate indicates a

high level of interest in these services.

We predict that the present growth will

continue at a 10% annual rate, driven by the usefulness of these services for private purposes. However,

if future licenses for these frequencies are issued by geographic areas–instead of by individual master

stations–it will be difficult to track growth in the same terms as before.

The MAS services described in this section

and other sections are shown in Figure 2.3-4.

Only the master station licenses are counted;

the remote stations are not independently

licensed and are ignored. The licenses counted

in this section, for example, does not include

remote stations in the 928-929 MHz band,

one-way MAS stations permitted in the

928.85-929 MHz band, master stations in the

952-953 MHz band, and any one-way MAS

stations licensed on a case-by-case basis

anywhere within the 928-929 and 952-953

MHz bands. The stations counted in Section

2.6 (952.85-960 MHz) include the point-to-point stations over most of the band and the MAS in the

959.85-960 MHz (master stations) and 956.25-956.45 MHz (one-way stations) bands. 
24

Figure 2.4-2. Bandwidth distribution chart for the

 932.5-935 MHz and 941.5-944 MHz bands.

932-935 & 941.5-944 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.4-1. Density of licenses in the 932-935 MHz and 941-944 MHz bands

2.4 Usage in the 932-935 MHz and 941-944 MHz Bands

Government, Private Operational, and Public Services

Typical users. This is a shared band, allowing private, public, and Government users. MAS operations

are allowed in the 932-932.5 MHz and 941-941.5 MHz parts of the band, with point-to-point operations

allowed in the rest of the band. Because of delays in licensing MAS operations, only point-to-point

operations are shown in the Geographical and statistical assignment information (Figure 2.4-1 and 2.4-2

and Table 2.4-1).

Table 2.4-1. Statistics for the 932.5-935 MHz

and 941.5-944 MHz Point-to-Point Bands Only

 total US assignments 3922

maximum assignment density 74

 effective number of channels 33.8

 average US channel reuse 116

 peak reuse/1-degree block 2.2

 annual growth rate (last 5 yr) 14.4%

 est. annual growth (next 5 yr) 10%

.

The 932.5-935 MHz and 941.5-944 MHz bands are used for point-to-point services, using pairs of

channels with bandwidths of 25 kHz, 50 kHz, 100 kHz, and 200 kHz. Figure 2.4-2 (above) shows the

distribution of licensed bandwidths for various types of NG users. Average bandwidth for all users is 148

kHz. Most of the non-Government assignments support paging systems. Of the total of 1395 Government
25

 Figure 2.4-3. Number of licenses in the 932-935 MHz

 and 941-944 MHz bands.

assignments, Agriculture has about 320

assignments (mostly for LMR

backbone), FAA has 600 assignments

(voice and data), DOE has 200

assignments (SCADA, telemetry, data),

and Interior has 85 assignments

(backbone, law enforcement, fire

suppression, etc.). 

Typical future MAS users are expected

to include numerous system control and

data acquisition (SCADA) uses, point-ofsale applications (check and credit card

verifications), security alarms, airport

runway lighting control, and many

miscellaneous applications. The MAS

segment of the band is channelized in

paired 12.5-kHz segments. MAS

licensing has been delayed, and the MAS part of the band remains empty.

Recent trends in number of assignments. Growth in the bands over the past eight years is shown in

Figure 2.4-3. Since no MAS licenses have been granted yet, this data represents only point-to-point

applications.

Comments. The MAS licensing has long been thwarted, beginning when the band was opened in 1990 and

the FCC received 50,000 initial non-Government license applications. Initially, the FCC determined that

a lottery would be used to choose license winners, but recently the FCC dismissed the 50,000 earlier

applications and has begun preparing to auction the MAS channels by geographical area (FCC NPRM; WT

Docket 97-82 released February 27, 1997). The auction date has not been set. The MAS bands will

probably be converted mainly to non-Federal, auctioned by 175 economic areas (EA’s), and used to

provide subscription-based commercial services. Five channel pairs will be reserved for Federal and Public

Safety users, to be available on a first-come basis. Although the band will be divided into 12.5 kHz

channels, rules will allow adjacent frequencies to be combined to provide bandwidths up to 100 KHz, and

probably will allow point-to-point and mobile services. No changes are being proposed for the point-topoint part of the bands.

Expected future growth rate. MAS license growth in this band will be instantaneous, as the logical

outcome of the auction process. However, since the channels will be licensed by geographical areas with

flexibility to aggregate frequencies and areas, future license count data may not be helpful in showing the

actual use of this band. We believe that the annual growth in operating master and remote stations should

exceed 10%, following a few initial years of faster growth. The point-to-point part of the bands should

grow by 10%/year for the next 5 years.
26

Figure 2.5-2. User bandwidths for the 

 944-952 MHz band.

944-952 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 or More

Figure 2.5-1. Density of licenses per square degree in the 944-952 MHz band.

2.5 Usage in the 944-952 MHz Band

Broadcast Auxiliary Service

Typical users. This band is used by FM broadcasters for aural studio-to-transmitter (STL) and inter-city

relay (ICR) links. The 25-kHz bandwidth channels can be stacked to give bandwidths up to 300 kHz, and

a single broadcasting station can use up to a total of 500 kHz. Average bandwidth is 342 kHz. Some of

this bandwidth can be leased for other broadcasting or non-broadcasting purposes. Geographical and

statistical assignment information are shown in Figure 2.5-1 and 2.5-2 and Table 2.5-1.

 Table 2.5-1. 944-952 MHz Band Statistics

 total US assignments 6174

 maximum assignment density 64

 effective number of channels 23.4

 average US channel reuse 264

 peak reuse/1-degree block 2.7

 annual growth rate (last 4 yr) 26%

 est. annual growth (next 5 yr) 20%
27

 Figure 2.5-3. Number of licenses in the 944-952 MHz band.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.5-3. The approximately 24% growth rate is due mostly to AM and FM broadcasters switching to radio

links as a way of bypassing the traditional equalized telephone lines, which are becoming expensive and

difficult to obtain. In addition, each broadcaster can apply for up to 500 kHz of spectrum, some of which

can be used to send nonbroadcast-related information to other customers.

Comments. Most of the growth is from FM broadcasters switching from existing dedicated equalized

telephone lines used as STLs. Many telephone companies have become reluctant to supply the specially

dedicated and carefully equalized telephone lines needed to carry high-fidelity stereo signals from the

studio to the transmitter site. Costs have become high and reliability has suffered, particularly when the

link passes through multiple telephone companies. Some broadcasters use a leased T1 link to carry a digital

stereo signal, but such lines are often as expensive as the high-fidelity analog lines, with typical monthly

charges in the $400-$1000 range.

Most STL radio equipment in this band

uses a 200-500 kHz bandwidth to carry

two audio signals (for stereo) and some

transmitter control signals. Although

most STLs are still analog FM, about

30% of new STLs use digital

technology. Some manufacturers

recommend single integrated links carrying a stereo signal; others use two

independent monaural transmitters, so

that one can serve as a backup (albeit

monaural only) if the other transmitter

chain fails. Still others put two stereo

pairs on a single link via digital

compression, a consolidation technique

that is useful under the new rules

allowing multiple local stations to be

operated by the same company.

The role of digital compression is key to putting more audio signals in a narrower bandwidth. MPEG-2

advanced audio coding (AAC), for example, requires only 128 kbits/s to carry broadcast-quality stereo.

However, some “golden ears” claim to notice artifacts and delays when any compression is used, causing

some stations to use extra bandwidth instead of compression.

Estimated future growth rate. We are estimating a 10% growth rate for this band into the next few years.

After a few years, however, wideband wireline digital transport technologies like ADSL or ISDN may

become much more available and economical on the public telephone system. When (and if) this occurs,

it could substantially decrease the use of radio for this purpose.
28

952-960 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.6-1. Density of licenses per square degree in the 952.85-960 MHz band.

Figure 2.6-2. User bandwidths for the

 952.85-960 MHz band.

2.6 Usage in the 952.85-960 MHz Band

Private Operational, Public, International Services

Typical users. This band contains MAS and point-to-point users. The MAS channels include 16 unpaired

channels near 956 MHz and 12 paired channels near 959 MHz (corresponding channels near 953 MHz).

See Figure 2.3-4. The twenty-eight 12.5-kHz bandwidth channels can also be used as fourteen 25-kHz

channels. Private operational point-to-point channels over the remainder of the band have bandwidths of

12.5 kHz, 25 kHz, 50 kHz, 100 kHz, and 200 kHz. The average bandwidth for all users is 99 kHz. The

point-to-point stations must use directional antennas. The MAS remote stations must use directional antennas, though the master stations can use omnidirectional antennas. Typical users of this band include general

SCADA applications to public safety; local water, gas, and electric utility companies; petroleum, utilities,

and railroads; as well as data applications for manufacturing, banking, and service providers. Geographical

and statistical assignment information are shown in Figure 2.6-1 and Table 2.6-1; bandwidth data is shown

in Figure 2.6-2.

 Table 2.6-1. 952-960 MHz Band Statistics

.

 total US assignments 8596

 maximum assignment density 93

 effective number of channels 72

 average US channel reuse 120

 peak reuse/1-degree block 1.3

 annual growth rate (last 5 yr) 6.9%

 est. annual growth (next 5 yr) 7%
29

Figure 2.6-3. Number of licenses in the 952-960 MHz band.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.6-3. The MAS data shows only MAS master stations; it does not include any information on MAS

remote stations. The private point-to-point services have grown 3% a year over the past 5 years. The MAS

services have grown 20% a year over the past 5 years. 

Comments. The relatively steady

growth rate shows a steady increase

in application. The MAS use of this

band was recently reviewed in an

FCC NPRM (WT Docket 97-81,

released 02/27,97), as part of a

study of MAS services. The 956.25-

956.45 MHz one-way MAS band

was found to be used mainly for

non-subscription services, and it

was decided to continue licensing

the use of these frequencies on a

similar basis as in the past. The

959.85-960 MHz master station

MAS band (paired with the 928.85-

930 MHz remote MAS band) was

found to be used mainly for

subscription services, and it was

proposed to auction future use of

this part of the band by Economic

Areas (EA’s). No changes were

proposed for the non-MAS parts of the band.

Estimated future growth rate. We estimate a 7% annual growth rate for all users over the next 5 years,

including a 4% growth rate for non-MAS point-to-point services in this band and a 20% growth rate in the

MAS services over the next 5 years.
 5

The 1385-1400 MHz portion of the Federal Government1350-1400 MHz band was transferred to

the FCC for allocation to non-Federal services, effective January 1999.

30

1350-1400 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 or More

Figure 2.7-1. Density of fixed assignments per square degree in the 1350-1400 MHz band.

Figure 2.7-2. Assignment density statistics.

2.7 Usage in the 1350-1400 MHz Band

Government Service

Typical users. The 1350-1385 MHz band is allocated exclusively to the Government for fixed, Mobile,

and Radiolocation services on a primary basis.5

 Footnotes restrict Government Radiolocation, fixed, and

Mobile services to military use. Other footnotes allocate 20 MHz to Aeronautical Radionavigation on a

primary basis, and on a secondary basis 30 MHz is allocated to passive Space Research and to Earth

Exploration Satellite services. Average bandwidth for fixed assignments is 1.1 MHz. Geographical and

statistical assignment information are shown in

Figure 2.7-1 and 2.7-2 and Table 2.7-1.

Table 2.7-1. Statistics for Fixed Assignments Only

 in the 1350-1400 MHz Band

 total US fixed assignments 507

 maximum assignment density 30

 effective number of channels 31

 average U.S. channel reuse 16

 peak reuse/1-degree block 0.97

 annual growth rate (last 4 yr) 1.7%

 est. annual growth (next 5 yr) 0.0%
31

Figure 2.7-3. Number of assignments in the 1350-1400 MHz band.

The Army currently has about 500 fixed assignments generally used for communications training, radio

relay, and RDTE (research, development, testing, and evaluation) support. The few remaining assignments

are for air traffic control, antenna testing, and ionospheric research. The 507 fixed systems have an

average bandwidth of 1.4 MHz and an average power of 20 watts. The frequency 1381.05 MHz is used

as a downlink channel for a nuclear detection satellite. This band also includes active air surveillance Lband radars. The Air Force and Navy each have a small number of assignments.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.7-3. The band was reallocated in the late 1980s to add fixed and mobile services to the existing

radiolocation service on a

primary basis. The military

took advantage of the new

allocation and moved a variety

of systems into the band. Overall assignments in the band

have grown by nearly 200%

from totals of 186 in 1987 to

709 in September 1998. Fixed

assignments have grown from 9

to 520 in this period. Since

1994, however, the number of

assignments in the band has remained relatively constant. 

Comments: This is a militaryonly Government band,

containing a variety of systems.

Some Federal assignments still

exist in the 1385-1400 MHz

part of the band.

Estimate of future growth:

The current use of the band is low, and the band use is expected to remain constant, not counting nonFederal licenses that may be moved into the upper 15 MHz of the band. 
 6

This band has been transferred to the FCC for commercial uses.

32

1427-1435 MHz

Transmitters per 1 Degree Block

1

2

4

Figure 2.8-1. Density of fixed assignments per square degree in the 1427-1435 MHz band.

Figure 2.8-2. Assignment density statistics.

2.8 Usage in the 1427-1435 MHz Band

Government Service6

Typical users. The 1427-1429 MHz band is shared by Government and non-Government users. Primary

Government allocations are to fixed, mobile, and space operations. The non-Government primary

allocation is to space operations, and secondary allocations are to land mobile (telemetering and telecommand) and to fixed (telemetering) operations. The 1429-1435 MHz band was allocated to the Government

for fixed and mobile on a primary basis, and non-Government allocation is to land mobile on a secondary

basis. In both bands, footnote G30 limits fixed and mobile services to the military forces, and footnote 722

alerts users to the existence of passive research

programs. 

Table 2.8-1. Statistics for Fixed Assignments Only

 in the1427-1435 MHz Band

 total US assignments 13

maximum assignment density 4

 effective number of channels 5.3

 average U.S. channel reuse 2.5

 peak reuse/1-degree block 0.75

 annual growth (last 5 yr) NA

 est. annual growth (next 5 yr) NA
33

Figure 2.8-3. Number of assignments in the

 1427-1435 MHz band.

investigating radio signals of possible extraterrestrial origin. Geographical and statistical assignment

distributions are shown in Figure 2.8-1 and Table 2.8-1, respectively.

The 1429-1435 MHz band is channelized (de facto) in 500-kHz increments, beginning at 1429 MHz,

though fixed systems have an average bandwidth of about 1.0 MHz. The main uses of the band are for

aeronautical telecommand of missiles, experimental testing, tactical communications and training, and light

route radio relay. The Air Force has assignments for such uses as radar cross-section measurement,

telecommand, and data link testing. The Navy has assignments for the testing of shipboard electronics,

control of remotely piloted vehicles, and research and testing. The Army has assignments that are for

tactical communications and training, and miscellaneous telemetry. Other agencies and non-Government

uses are in administration, antenna testing, and with Voice of America. The automobile industry has

multiple assignments as part of an automation and manufacturing development effort. Almost half of these

non-Government assignments are for use in all parts of the United States.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Fig 2.8-3.

Total assignments in the 1427-1435 MHz band grew from 53 in 1987 to 180 in at the end of 1997. 

Comments. This band was

identified for reallocation to nonFederal use, effective January

1999. As shown in Table 2.8-1

(data current as of September

1998), only 14 fixed Federal

assignments are left in the band.

However, fixed Federal

assignments have always been a

relatively small part of the band

usage.

Estimated future growth rate.

Since no proposed reallocation

plans are known at this time, it is

difficult to estimate future growth.

Although this band is currently

subject to reallocation, presumably

many of the existing assignments

will remain until the band is

actually reallocated and new uses

are identified for the band.
 7

The Federal Government will transfer the 1710-1755 MHz part of this band to the FCC in 2004

for allocation on a mixed basis with non-Federal services.

34

1710-1850 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.9-1. Density of fixed assignments per square degree in the 1710-1850 MHz band.

Figure 2.9-2. Assignment density statistics.

2.9 Usage in the 1710-1850 MHz Band

Government Service7

Typical users. The 1710-1850 MHz band is the Federal Government’s general-purpose, long-range, lowcapacity, point-to-point microwave band, typically providing a remote location with a small number of

voice channels or digital control/monitoring channels. Bandwidths vary from 0.5 MHz to 10 MHz, with

the average fixed user bandwidth equal to 3.4 MHz. Footnotes limit Government fixed operations and

provide for space operations on an equal basis with fixed and mobile, and allow the earth explorationsatellite service on a non-interference basis. Geographical and statistical assignment distributions are shown

in Figures 2.9-1 and 2.9-2 and Table 2.9-1. 

 Table 2.9-1. 1710-1850 MHz Band Statistics

 total US fixed assignments 6237

 maximum assignment density 147

 effective number of channels 41.5

 average US channel reuse 150

 peak reuse/1-degree block 3.5

 annual growth rate (last 5 yr) 0.5%

 est. annual growth (next 5 yr) -1%
35

Figure 2.9-3. Number of assignments in the

 1710-1850 MHz band.

Typical uses for this band include SCADA for electrical power, locks, and dams (TVA, Bonneville Power

Administration (BPA), and Army Corps of Engineers), military test ranges (Edwards AFB, White Sands

Missile Range, etc.), backbone for communications in remote areas (including National Forests and

National Parks), transportable microwave communication terminals (military services), and many

miscellaneous uses. This band is also used for airborne telemetry and satellite applications.

The Army has 1,790 fixed assignments

used for backbone voice and data,

administrative, tactical and training, and

weather data. The Air Force has 470 fixed

assignments used in backbone

communications, system testing, the

Satellite Ground Link System (SGLS), Air

Combat Maneuvering Instrumentation

(ACMI), and video data links. The Navy

has 400 fixed assignments used for lineof-sight diversity links, telemetry, tactical

training, video links for missile

evaluation, and testing of shipboard electronics. Agriculture has 1,180 fixed

assignments used for LMR backbone or

National Forest management. Justice has

620 fixed assignments, mainly for LMR

backbone. Energy has 750 fixed

assignments connected with SCADA, law

enforcement or communications with nuclear sites. The FAA has 390 assignments, used mainly for various

aspects of air traffic control. Interior has 250 fixed assignments used in law enforcement, resource

management, SCADA, and fire suppression. The 100 TVA assignments are used mainly for SCADA for

electrical power networks. 

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.9-3. This reflects a gradual replacement of some agency-specific microwave communications with optical

fiber or commercial services. More than 800 assignments were added in 1992 due to a policy change,

which resulted in individual assignments for transportable military microwave terminals. The FAA has

added 300 fixed assignments for Low Data Radio Communication Links, with up to 4 DS-1 channels each.

Comments. The Government's need to provide specialized long range communication services to many

remote locations ensures that this band will continue to remain heavily used.

Estimated future growth rate. The 1710-1755 MHz portion of this band has been offered for mixed

Federal/non-Federal use, beginning in 2004. About 330 microwave sites supporting the Federal Power

Agency electrical distribution system are exempt from moving. Other users could be retuned to the

remaining 1755-1850 MHz part of the band or moved to the 7-8 GHz band. Licenses for non-Federal use

of the band may be auctioned, and Federal users displaced from this band will be compensated to move

to other frequencies by the new licensees. Growth of the shared portion of the band and future Federal

migration from the shared portion will depend partly on future FCC allocation decisions. The total Federal

use of the band will continue a 1% annual rate of decrease, not counting any net migration from the shared

portion of the band.
 8

The FCC has reallocated this band for PCS and other emerging technologies.

36

Figure 2.10-2. License density statistics.

1850-1990 MHz

Transmitters per 1 Degree Block

1 to 2

3 to 5

6 to 19

20 to 59

60 or More

Figure 2.10-1. Density of fixed licenses in the 1850-1990 MHz band.

2.10 Usage in the 1850-1990 MHz Band

Private Operational Service8

Typical users. The 1850-1990 MHz band was allocated to the private operational services. Typical uses

include a wide range of system control and monitoring applications (typically used for railroads, petroleum

pipelines, and electrical utilities), as well as more general data and voice communications for local and

state government (especially to support public safety wide-area mobile radio), and private business. Typical

users (and number of licenses) in this band include electrical utilities (3,197), petroleum (2,487), public

safety and local government (2,011), railroads (895), and others (668) (Marrangoni, [9]). This band is

channelized for 5-MHz and 10-MHz channels, with an average 1998 bandwidth of 9.3 MHz. 

Table 2.10-1. 1850-1990 MHz Band Statistics

 total US assignments 3530

 maximum assignment density 57

 effective number of channels 15

 average US channel reuse 235

 peak reuse/1-degree block 3.8

 annual growth rate (last 3 yr) -0.6%

 est. annual growth (next 5 yr) -15%
37

Figure 2.10-3. Number of fixed licenses in the 

 1850-1990 MHz band.

Recent trends in number of assignments. Change in this band over the past 11 years is shown in Figure

2.10-3. This band was reallocated by the FCC for PCS systems and auctioned to PCS providers in early

1995; this graph does not include any new

PCS systems. The decrease in 1996

represents incumbent fixed users being

moved out to make room for new PCS

users. Since PCS systems were introduced

first in urban areas, the existing microwave

systems were removed first from urban

areas. Thus, many of the urban

concentrations of the microwave systems

are now gone, while relatively more rural

systems remain. Figure 2.10-1 shows an

unusually even distribution of systems.

Comments. The FCC has provided for

new channelization and eligibility rules in

other point-to-point microwave bands at

higher frequencies to facilitate migration of

current 1850-1990 MHz band users to

those bands.

Many of these microwave networks were originally built in the 1960's and 1970's to support SCADA

operations for a particular pipeline, railroad, or electrical power grid. Often the existing microwave link

works well and can economically provide limited bandwidth communications service, particularly in the

case where full-time monitoring of a narrowband circuit is needed. High reliability is a major requirement

for many users of this band, in support of time-critical utilities operations as well as safety-of-life

operations in the public safety field. For many of these users, fiber optics is not a reasonable alternative,

unless redundant fiber circuits can be employed to guarantee operation even when the fiber is accidently

cut. Fiber is not normally price-competitive for the narrow bandwidths that are often used here, and the

need for redundancy makes it even more expensive.

Some of these SCADA users had access to right-of-way over great distances, and these systems became

the routes (or remain potential routes) for fiber-based independent IXC’s. 

Estimated future growth rate. This band is now part of the new PCS bands, which means that most of

the remaining fixed microwave links will soon be moved out to make room for PCS. The incumbent fixed

population began a rapid decline in 1996 as they were shut down by A-Block and B-Block PCS systems.

The trend will continue strongly, as additional PCS systems are built. Some of the existing rural links may

be left in the band longer, since there will be less immediate demand for rural PCS. 
 9

The FCC is in the process of reallocating a portion of this band to mobile satellite services (MSS).

See Section 1.8.

38

1990-2110 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.11-1. Density of licenses per square degree in the 1990-2110 MHz band.

Figure 2.11-2. License density statistics.

2.11 Usage in the 1990-2110 MHz Band

Broadcast Auxiliary Service and CARS (ENG-only)9

Typical users. Typical users of this band include local TV broadcasters, national network TV, and cable

relay system (CARS) operators. This band is used for electronic news gathering (ENG), studio-totransmitter links (STL), intercity relay (ICR), and transmitter-to-studio links (TSL). In all cases, the 6-

MHz-wide NTSC signal is frequency-modulated on a 17-MHz-wide channel. The band is crowded in

major TV market areas, and ENG may be coordinated among broadcasters on an hour-by-hour basis

between TV channels, particularly during major scheduled or unscheduled events. Although alternative

higher frequency

 Table 2.11-1. 1990-2110 MHz Band Statistics

 total US licenses 3142

 maximum assignment density 104

 effective number of channels 7

 average US channel reuse 449

 peak reuse/1-degree block 15

 annual growth rate (last 5 yr) 8.9%

 est. annual growth (next 5 yr) 9%
39

Figure 2.11-3. Number of licenses in the

 1990-2110 MHz band.

bands exist for these functions, the 2 GHz band is usually preferred for ENG. Geographical and statistical

license information are shown in Figures 2.11-1 and 2.11-2 and Table 2.11-1.

Recent trends in number of

assignments. Growth in this band over

the past 11 years is shown in Figure

2.11-3. This growth is due to a

continuing increase in the popularity of

"live" coverage of local events by TV

broadcasters (ENG). 

Comments. Broadcasters claim that

this band is already very crowded, and

that providing support for additional

HDTV or multiple SDTV channels will

be very difficult. On the other hand, it

is likely that technical solutions will

become available in the form of digital

compression and increased availability

of optical fiber and other broadband

media. Some broadcasters have tried to

replace crowded ENG operations with

satellite news gathering (SNG)

equipment, with varying degrees of

success.

The FCC is in the process of converting 35 MHz of this band into the mobile satellite service (MSS) (ET

Docket 95-18), as described in Section 1.9. The FCC believes that digital compression techniques will

allow terrestrial ENG to be squeezed into 12-MHz channels; therefore, the existing 7 channels could be

included within 85 MHz of spectrum (2025-2110 MHz) and 35 MHz could be diverted to MSS and other

auctioned wireless licenses. While this claim seems reasonable (since HDTV can be fit within a 6-MHz

channel), broadcasters note that digital compression is a “lossy” process and that every successive use of

compression further impairs accurate reproduction of the original signal. Although new ENG equipment

would be needed for digital compression, the FCC proposes that it should be paid for by the new MSS and

wireless users. Vigorous discussion continues on the details of how new users would reimburse

broadcasters for required new equipment, and whether the changeover to narrowband ENG should be

gradually implemented or staged at particular times. 

Expected future growth rate. Additional local programming to support cable networks and other new

participants will surely increase the demand for ENG. It is likely that growth of 2-GHz ENG will continue,

but some of the 2-GHz ICR and STL use will be shifted to higher frequency bands or to fiber. We believe

that wideband commercial services (e.g., CLEC fiber, 24 GHz and 39 GHz bands, and xDSL) will

eventually provide some alternatives to ENG in major metropolitan areas. Finally, we believe that this

rechannelization will cause a wave of DTV-related changes, including purchases of new digital ENG

equipment, conversion of some analog STLs to digital, development of cosited transmitter complexes

(possibly served with fiber), etc. Some of these changes will add equipment to this band; other changes

will subtract equipment. Lacking more detailed insight, we predict the same growth rate (9 percent) to

continue for the next 5 years.
 10This band has been identified by the FCC for future reallocation to emerging technology services. 

40

Figure 2.12-2. User bandwidths for 2110-2130

 and 2160-2180 MHz bands. 

2110-2130 & 2160-2180 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.12-1. Density of licenses in the 2110-2130 MHz and 2160-2180 MHz bands.

2.12 Usage in the 2110-2130 MHz and 2160-2180 MHz Bands

Public Service10

Typical users. Typical users of these bands include low density telephone links, especially trunks and

feeders between cellular sites and connections to the local exchange carrier. This allocation includes a pair

of frequency bands, each having six 3.2-MHz channels or five 3.6-MHz channels. Average user bandwidth

is 3.2 MHz. Modern 256-QAM equipment permits up to 12 DS-1 signals on each channel. Geographical

and statistical license information are shown in Figures 2.12-1 and Table 2.12-1. Bandwidth information

is shown in Figure 2.12-2.

Table 2.12-1. Statistics for the 2110-2130 MHz 

 and 2160-2180 MHz Bands 

 total US assignments 9708

 maximum assignment density 69

 effective number of channels 12.6

 average US channel reuse 768

 peak reuse/1-degree block 5.4

 annual growth rate (last 3 yr) -1.9%

 est. annual growth (next 5 yr) gone
41

2360

3059

3922

5335

6329 6277

8171

4671 4731 4442

4040

5580 5535 5694

5648

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

0

2000

4000

6000

8000

10000

12000

cellular only

common carr

 Figure 2.12-3. Number of licenses in the 2110-2130 MHz

 and 2160-2180 MHz bands.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.12-3. This band has been used for many years as a low-capacity feeder for telephone service. Recently,

it has experienced rapid growth in support of cellular networks. Many cellular providers have chosen to

build a complete and independent network for their cellular

system, providing complete

bypass of the LEC. The low

cost and low bandwidth of the

2 GHz band is ideally suited to

many of the low bandwidth

connections needed between

cellular sites.

The momentary dip in growth

in 1992 was caused by

uncertainty about the rules and

timing of the reallocation for

PCS; strong growth returned

when industry understood that

several years remained before

the band would be used by

PCS. Because the 2 GHz band

was one of the few bands

available to common carriers

that was channelized for the

low-capacity links, industry

chose to continue intensive use

of this band, counting on rapid economic payback even if the band would need to be vacated after several

years. Recently, however, users have chosen to move new links into more permanent bands.

Comments. This band is part of the "emerging technologies" bands identified by the FCC for future

auction to PCS and MSS systems, and current users will need to find alternative frequency bands. Because

of the continuing reduction in cell size, microwave links between cellular sites are continually getting

shorter and many users will not specifically require the long-range capabilities of 2 GHz. The FCC has

recently made available to common carriers narrowband channels in the 6 GHz, 6.5 GHz, 10.5 GHz, 11

GHz, and 18 GHz bands. These bands will be used to service most new cellular construction, and they will

serve as migration destinations for existing 2-GHz systems.

Estimate of future growth. Growth of fixed services in this band has stopped, as carriers face the

impending reallocation of this band to other services (see details in section 1.8). The number of fixed

licenses will drop rapidly several years from now, when they will be displaced by other services, including

MSS and a general-purpose auctioned band. However, the associated auctions and other reallocation

activities have not yet been scheduled. In the meantime, much existing 2-GHz equipment will continue to

be used and re-used, especially in rural locations where long range is needed and where new terrestrial

PCS might not be as rapidly deployed. Note, however, that MSS will be especially useful in rural areas

and that the large coverage area of MSS requires very large areas to be cleared of existing systems before

there can be any use of MSS.
 11This band has been identified by the FCC for future allocation to PCS and other emerging

technology services. See Section 1.8.

42

2130-2150 & 2180-2200 MHz

Transmitters per 1 Degree Block

1 to 2

3 to 9

10 to 29

30 to 99

100 or More

Figure 2.13-1. Density of licenses in the 2130-2150 MHz and 2180-2200 MHz bands.

Figure 2.13-2. License density statistics.

2.13 Usage in the 2130-2150 MHz and 2180-2200 MHz Bands

Private Operational Services11

Typical users. This private operational microwave band has paired sub-bands, each with 24 channels of

800 kHz or 1.6 MHz (using adjacent channels) bandwidth and a maximum power of 20 watts. Average

bandwidth is 1.38 MHz. Typical users include local government and public safety (4,052), utilities

(3,521), petroleum (2,933), railroads (991), and others (1,538) including manufacturing, banking, and

service providers (Marrangoni, [6]). Typical uses include SCADA and internal corporate communications.

 Table 2.13-1. Statistics for the 2130-2150 MHz

 and 2180-2200 MHz Bands

 total US assignments 11,639

maximum assignment density 117

 effective number of channels 28.9

 average US channel reuse 403

 peak reuse/1-degree block 4.1

 annual growth rate (last 3 yr) -4.0%

 est. annual growth (next 5 yr) gone
43

 Figure 2.13-3. Number of licenses in the 2130-2150 MHz

 and 2180-2200 MHz bands.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.13-3. The growth stopped in 1991 when the FCC earmarked this band for future conversion to emerging

technologies. Since that time, there has been slow attrition, as present users implement new construction

in bands that will allow permanent

installations. In addition to the

change in the numbers of licenses

shown here, there has been

considerable activity from users

who are upgrading older analog

equipment for newer digital

equipment. Many users have upgraded receiving equipment to

multilevel digital modulation, so

that each channel can transport

information more flexibly than

previously, mixing such services

as voice and data, etc. 

Comments. This band is part of

the Emerging Technology bands,

reallocated recently by the FCC

for MSS and other auctioned wireless systems (see details in Section

1.9). This band was used

extensively for SCADA applications, many in rural areas where

the long-range capability of the 2 GHz band was needed. Since it is known that all new applications in this

band can remain only until the band is reallocated for other services, new construction has moved to other

bands. On the other hand, some present users may be holding on to existing 2 GHz systems in anticipation

of future buyouts by new users, who might be required to pay for a move to another band. The FCC has

provided for narrowband and wideband channelization in the 4 GHz, 6 GHz, 6.5 GHz, 10.5 GHz, 11

GHz, and 18 GHz bands as possible migration bands for systems displaced from 2 GHz.

Estimated future growth rate. The use of this band for point-to-point microwave will continue to

decrease slowly by attrition for the next several years. New system deployments and modernization will

be performed mainly in other bands. The use will decline more rapidly when the new MSS and generalpurpose auctioned wireless services begin to displace current users. In the meantime, much existing 2-GHz

equipment will continue to be used and re-used, especially in rural locations where long range is needed

and where new terrestrial PCS might not be as rapidly deployed. Note however that MSS will be used

especially in rural areas and that the large coverage area of MSS requires very large areas to be cleared

of existing systems before there can be any use of MSS.
44

 total US licenses (1993 data) 279

 maximum assignment density 6

 effective number of channels 2

 average US channel reuse 139

 peak reuse/1-degree block 3

 Table 2.14-1. 2150-2160 MHz Band Statistics 

MDS

Transmitters per 1 Degree Block

1

2 to 3

4 to 6

Figure 2.14-1. Density of licenses per square degree in the 2150-2160 MHz band (1993 data).

2.14 Usage in the 2150-2160 MHz Band

Public (Multipoint Data Service), and Private

Typical users. This band is allocated for multipoint data service (MDS), originally intended to distribute

digital data on a point-to-multipoint basis. The intended digital data service never developed, and the band

became part of the multichannel multipoint distribution system (MMDS) system (see Section 2.17). Two

6-MHz channels of MMDS "wireless cable" TV channels are available by extending the band to 2162

MHz. (The band can be extended to 2162 MHz only near major metropolitan areas, and only when it will

not cause interference to existing public point-to-point stations in the 2160-2162 MHz range.) MDS stations

usually use omnidirectional transmitting antennas with total power less than 10 watts per channel (up to

100 watts per channel with permission). All license data is 1993 information from Dataworld, Inc.

The creation of MMDS in the 2500-2690

MHz band (see Section 2.17) has allowed the

2150-2160 (or 2150-2162) MHz band

channels to be incorporated as part of the 33-

channel package available to an MMDS

operator. Digital compression and 2-way

operation will add even more possibilities.

Some MMDS operators have proposed using

the MDS channels as reverse (response)

channels for 2-way digital MMDS. This

makes some sense, since it is somewhat

inconvenient to split the MMDS downstream

video channels into two frequency bands,

while the frequency separation would be desirable between MMDS transmitter and receiver functions.

Private microwave operators are also allowed to use this band, using directional antennas only.
45

MMDS Transmitters per 1 Degree Block

1

2 to 3

4 to 6

Figure 2.14-2. Geographical distribution of MMDS licenses

 (2500-2690 MHz, Section 2.17).

ITFS

Transmitters per 1 Degree Block

1

2 to 3

4 to 6

7 to 12

13 or More

Figure 2.14-3. Geographical distribution of ITFS licenses

 (2500-2690 MHz, Section 2.17).

Recent trends in number of assignments. We do not have historical licensing information in this band,

which has been lightly used in the past. The allocation rules have recently been changed, incorporating this

band as part of the MMDS wireless cable service, 2500-2690 MHz band, Section 2.17.

Comments. One of the FCC's purposes in setting up MDS/MMDS was to provide a wireless alternative

to cable TV, thus introducing additional competition into the cable market. The growth rate will be tied

to new MMDS systems. However, analog TV distribution by MMDS has only been marginally successful,

with most future hope now placed on new digital versions that will provide general-purpose 2-way

broadband digital service.

The geographical

distribution of channels

used for MMDS is shown

in Figure 2.14-2. Note that

MMDS systems are widely

distributed in rural areas,

where they are used to

economically provide

multichannel TV service

with a lower density of

customers than cable TV.

Recently, however, rural

customers are switching to

BSS delivery of TV

programming.

MMDS also shares the

2500-2690 MHz band with

instructional TV fixed

service (ITFS) used to relay

video classroom lectures to

public schools, colleges,

and industry. Figure 2.14-3

shows the geographical

distribution of ITFS

licenses. Note the wide

variation between states,

reflecting a variety of

policies by various state

Departments of Education.

Estimated future growth

rate. Future growth of the

MDS band is highly

dependent on growth of the MMDS services, where it can function as additional MMDS channel capacity

or as an upstream return path for 2-way use. See more details in Section 2.17. 
46

2200-2300 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 or More

Figure 2.15-1. Density of fixed assignments per square degree in the 2200-2300 MHz band.

Figure 2.15-2. Assignment density statistics.

2.15 Usage in the 2200-2300 MHz Band

Government Service

Typical users. The 2200-2290 MHz band is Government exclusive and is allocated on a primary basis to

fixed, mobile and space research. Footnotes give non-Government space research rights to transmit to the

TDRSS satellite on a non-interference basis and give space operations co-equal status with the other primary

allocations. The 2290-2300 MHz band is shared by Government and non-Government. Government has

primary allocations to space research, fixed and mobile services; non-Government allocations are to space

research on a primary basis. This band was stated to be unavailable for reallocation to non-Government

functions because of national defense priorities. Publicly announced users include point-to-point microwave,

airborne, mobile, and satellite applications. Geographical and statistical assignment distributions are shown

in Figure 2.15-1 and Table 2.15-1, respectively.

Table 2.15-1. 2200-2300 MHz Band Statistics

 total US fixed assignments 306

maximum assignment density 19

 effective number of channels 22

 average US channel reuse 104

 peak reuse/1-degree block 0.86

 fixed growth rate (last 3 yr) 0%

 est. annual growth (next 5 yr) 0%
47

 Figure 2.15-3. Number of assignments in the 

 2220-2300 MHz band.

The 2200-2300 MHz band is heavily used by the Government in space, deep space, and terrestrial

telemetry, telecommand and control. NASA uses the band with the TDRSS satellite, and the Air Force uses

the band with the Space Ground Link Subsystem (SGLS). It is the primary downlink band for Government

satellite systems operating in the 1710-1850 MHz and 2025-2110 MHz uplink bands.

The total assignment count in September 1998 was 2,272, of which fixed assignments totaled 298. The fixed

assignments are mainly used for microwave service in conjunction with land mobile systems for voice and

data in remote areas. The fixed assignments have an average bandwidth of 4.5 MHz.

The Air Force has 900 assignments

for uses such as telemetry, missile

testing, miscellaneous space activities,

and electronic warfare testing. The

Navy has 410 assignments for missile

telemetry, inter-ship data relay, range

operations, and atmospheric research

telemetry. The Army has 350

assignments for backbone, testing,

Global Positioning System, and

RDTE support. Energy has 260

assignments for flight telemetry, data

links, and other program telemetry.

NASA's 170 assignments are for

sounding rocket telemetry, command

and tracking for Voyager 2, and for

communication with the TDRSS

satellite. The remaining 140

assignments are used for law

enforcement, resource management,

and spacecraft monitoring

communications. 

The Army has the largest number of fixed assignments (86), followed by Coast Guard (33), Air Force (28),

Justice (27), Navy (26), Energy (24), and others.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.15-3. The total number of assignments and the number of fixed assignments in the 2200-2300 MHz band

have remained essentially constant over the last five years.

Comments. The number of fixed assignments has been quite stable. Note that only about 13% of the

assignments in this band are for the fixed services, however. 

Estimated future growth rate. The fixed use is expected to be constant or to decrease slightly over the

next 5 years.
48

2450-2500 MHz

Transmitters per 1 Degree Block

1

2 to 4

4 to 11

12 to 39

40 or More

Figure 2.16-1. Density of licenses per square degree in the 2450-2483.5 MHz band.

Figure 2.16-2. License density statistics.

2.16 Usage in the 2450-2483.5 MHz Band

ISM, Government, Auxiliary Broadcast, and Private Services

Typical users. This ISM band has a wide variety of Government and non-Government functions. Since this

band is assigned on a primary basis to the industrial, scientific, and medical (ISM) service, no other service

has any protection from interference from ISM devices. The FCC has recently allowed spread spectrum

communications in this band with up to 1 watt of power (without licensing or protection), and many

experiments are underway for wireless LANs, PCS, and other spread-spectrum systems. Private operations

have 30 pairs of channels with 800-kHz bandwidth over the 2450-2500 MHz band. BAS has two 17-MHz

channels over the 2450-2483.5 MHz band. The band is also allocated on a secondary basis for nonGovernment radiolocation, on a primary basis for mobile, and on a non-interfering basis (via a footnote)

for Government radiolocation. Geographical and statistical assignment distributions are shown in Figures

2.16-1 and 2.16-2 and Table 2.16-1.

Table 2.16-1. 2450-2483.5 MHz Band Statistics

 total US licenses 758

maximum license density 36

 effective number of channels 4.4

 average US channel reuse 173

 peak reuse/1-degree block 8.2

 annual growth rate (last 4 yr) 12.6%

 est. annual growth (next 5 yr) 10%
 12C. Phillipi, R. Hinkle, K. Nebbia, B. Ramsey, F. Sanders, “Accommodation of broadcast

satellite (sound) and mobile satellite services in the 2300-2450 MHz band. NTIA technical

memorandum, NTIA TM-92-154. January 1992.

49

35 58 50 67 82 89

119

209 225 250

385

300

358

399

411

441 437

450

559

288

306

328

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997

0

100

200

300

400

500

600

700

800

Private

BAS

Figure 2.16-3. Number of licenses in the

 2450-2483.5 MHz band.

The most notable ISM use is for 80 million microwave ovens, operating at a nominal 2450 MHz, whose

signal leakage raises the apparent background noise level over most of this band.12 The two sets of

numbers for number of channels and channel reuse are for BAS and Private Operational, respectively.

Recent growth in number of assignments. Growth in this band over the past 11 years is shown in Fig

2.16-3. This data shows the number of licensed microwave assignments. In 1987, there were 35 BAS

assignments and 300 private operational

assignments, which grew (respectively) to 328

and 385 in 1997. While the number of

narrowband private licenses grew by less than

2% per year, the number of BAS licenses grew

by about 27% per year. It should be noted,

however, that the overwhelming majority of

transmitters in this band are non-licensed ISM or

low-power devices, which are not shown here. 

Comments. This band was originally allocated

to 2500 MHz. In 1985, a non-Government radiolocation satellite service was allocated to the

2483.5-2500 MHz portion of the band, but existing BAS and private stations were "grandfathered." The license counts include grandfathered stations in the 2483-2500 MHz band. 

A recent change in FCC rules allows this band to

be used by non-licensed Part 15 spread-spectrum

communication systems with up to 1 watt of power and high-gain directional antennas. This band is

currently the band of choice for much deployment of unlicensed wireless LANs and point-to-point fixed

systems. The unlicensed point-to-point microwave links in this band may already greatly outnumber the

licensed links, including some in use for cellular and broadcast audio STLs. With the conversion of the 2

GHz microwave bands to PCS, this band is currently one of the lowest frequency bands for long-distance

microwave links. The geographical location of licensed fixed stations in the Gulf of Mexico shows one way

that cautious users avoid the possibility of interference from normally-land-based microwave ovens. 

Estimated future growth rate. Since most of the transmitters in the band are nonlicensed, the number of

licensed transmitters may not show much about band use. The number of microwave ovens will continue

to grow slowly. Significant numbers of new ISM devices (e.g., microwave light bulbs) are possible. The

number of nonlicensed wireless LANs and point-to-point systems using spread-spectrum technology will

grow rapidly (30%/year), though these numbers will not appear in license databases. Interference from

other unlicensed devices (e.g., Bluetooth and cordless phones) might cause future problems. Unfortunately,

there is little historical experience to estimate how or when this “noise build-up” will occur. The recent

availability of additional narrowband channels in rechannelized licensed fixed service bands may make this

band a less attractive choice. Licensed private and BAS systems will continue to grow at the combined rate

of 10%/year. 
50

 total US licenses (1993 data) 1548

maximum license density 23

 effective number of channels 31

 average US channel reuse 50

 peak reuse/1-degree block 0.7

 Table 2.17-1. 2500-2690 MHz Band Statistics

MMDS+ITFS+OFS

Transmitters per 1 Degree Block

1

2 to 3

4 to 6

7 to 12

13 or More

Figure 2.17-1. Density of licenses per square degree in the 2500-2690 MHz band.

2.17 Usage in the 2500-2690 MHz Band

Broadcast Auxiliary, Public, and Private Operational Services

Typical users. This band is allocated for several types of services, including wireless cable TV broadcasting

(MMDS), instructional TV fixed service (ITFS), private operational fixed service (OFS), and narrowband

audio response channels. Figure 2.17-1 shows the sum of licenses in the first three services. Additional

separate maps for MMDS and ITFS are shown in Section 2.14. All license data is 1993 data from

DataWorld, Inc. Figure 2.17-2 shows how services are arranged in the frequency band. MMDS wireless

cable was created in 1983 to provide a wireless alternative to cable TV. It also has application to rural

areas, where the population density cannot support the capital investment needed for a cable system. The

1990 regulations permitted use of up to 33 channels (including 2 channels in the 2150-2162 MHz band),

allowing MMDS to compete better with cable.

Instructional TV Fixed Service (ITFS), Part 74, BAS. ITFS originally filled the entire band with six

groups (Groups A-H) of four 6-MHz channels. Group H was converted to private use in 1970. Groups E

and F were converted to MDS in 1983, but existing ITFS channels were grandfathered. One ITFS owner

could have only one group of four channels.

ITFS is intended for TV classroom instruction,

e.g., when a local university brings in-house

classroom instruction to the employees of a

local corporation.

Multichannel, multipoint distribution service

(MMDS), Part 21, Public. Although MMDS

has only 10 channels (8 channels in 2596-

2644MHz and 2 MDS channels in 2150-2162

MHz ), 20 ITFS channels and 3 private

operational channels can be added. These 33
51

A1 A2 A3 A4

B1 B2 B3 B4

C1 C2 C3 C4

D1 D2 D3 D4

E1 E2 E3 E4

F1 F2 F3

ITFS MMDS

 1 

 2 

MDS

25722524 2596250021622150 2548

F4

2620 2644 2668 2690 2684

G2G1 G3 G4

H1 H2

ITFS/OFS

 ITFS 

MDS, MMDS

OFS

CFR 47, PART 21

- COMMON CARRIER BUREAU

CFR 47, PART 74

- PRIVATE RADIO BUREAU

CFR 47, PART 94

MASS MEDIA BUREAU

J

K

MMDS

ITFS

OFS

SERVICE

1 & 2 (ORIGINAL)

E & F (NEW)

A, B, C, D. G

H

2

8

20

3

TOTAL 33

CHANNEL

ALLOCATION

NUMBER OF

CHANNELS

H3

31 RESPONSE CHANNELS, EACH 125 KHZ BANDWIDTH

R

Figure 2.17-2. Service allocations in the 2500-2690 MHz band.

channels can be broadcast from

omni-directional antennas with up to

100 watts per channel. The directional

receiving antennas and converter box

are typically rented to the customer,

as part of the general service fee.

ITFS channels are sometimes

borrowed by MMDS operators, who

furnish transmitters to the ITFS

operator during the workday, in

exchange for use of the ITFS

channels after 5:00 p.m.

Response channels, 2686-2690

MHz, Part 21, Public. These 28

channels (each 125-kHz wide) are

used to provide an upstream audio

response path (e.g., from classroom student to instructor) for each downstream video channel in the band.

Others have proposed using the MDS band or the 2.3 GHz WCS band for upstream channels, providing

greater receiver and transmitter frequency separation and wider bandwidths.

Operational fixed service, Part 94, Private. This includes three channels between the four Group G ITFS

channels.

Recent growth in number of assignments. A 1990 FCC rule change permitted MMDS operators to hold

multiple MMDS groups. License information from Dataworld, Inc. in 1993 showed totals of 680 ITFS, 279

MDS, 294 MMDS, and 574 private licenses. All remaining E-, F-, and H-group MMDS licenses were

auctioned in 1996, for a total auction price of $216 million. The Wireless Communication Association

International web site showed 250 MMDS systems on July 1998 with 1.1 million U.S. customers. 

Comments. Some observers believe that 33-channel analog MMDS will not prosper, since many past

customers have recently switched to 12-GHz broadcast satellite service (BSS) technology using small-dish

antennas and digital compression. In 1998, the FCC permitted MMDS to use multiple low power transmitter

sites, compressed digital modulation, and two-way transmission [10]. This would allow MMDS to become

a longer-range version of LMDS, providing many digital video channels, telephone, and wideband Internet

access. The MMDS industry is making a major effort to change, since many MMDS providers are currently

facing fiscal difficulties and eroding customer bases. In one vision, digital MMDS would compete directly

with BSS (with the added MMDS advantages of local TV channels, Internet, and telephone). BellSouth

began operation of 160-channel digital TV systems in several metropolitan areas in 1998, and several

companies are offering high-speed downstream Internet access (some using a telephone return path). In

another vision, MMDS would drop consumer TV and concentrate on broadband urban digital service for

Internet, business, and telephone use, using many of the technologies being developed for LMDS and aimed

at the same market. 

Estimated future growth rate. It is still very unclear whether MMDS will succeed against competing

technologies. If MMDS is successful in the U.S. in the future, it will be through two-way digital services

in urban areas, spreading to rural areas, possibly with active cooperation from LMDS operations.
 13This band has been recently reallocated to allow private operations.

52

Figure 2.18-2. License density statistics.

3700-4200 MHz

Transmitters per 1 Degree Block

1 to 5

6 to 19

20 to 59

60 to 199

200 or More

Figure 2.18-1. Density of licenses per square degree in the 3700-4200 MHz band.

2.18 Usage in the 3700-4200 MHz Band

Public and Private Operational Services13

Typical users. This band was the original long-haul microwave band, providing an analog transcontinental

network for television and long-distance telephone circuits. As this band filled up, the overflow went into

the 6 GHz band, which was designed to share waveguides and antennas with the 4-GHz network. This band

is channelized at 20-MHz spacing The early analog equipment has mostly been upgraded with digital

equipment or replaced with fiber optics. The band is also shared with large numbers of licensed and

nonlicensed fixed-satellite downlinks, which are used in TV, TVRO, and digital services. Although this

band was recently reallocated to include private operators, it remains channelized at 20 MHz only.

Geographical and statistical assignment distributions are shown in Figure 2.18-1 and Table 2.18-1,

respectively.

Table 2.18-1. Statistics for Terrestrial Licensees

 in the 3700-4200 MHz Band

 total US terrestrial licenses 11,701

 maximum licenses density 131

 effective number of channels 25

 average US channel reuse 468

 peak reuse/1-degree block 5.2

 annual growth rate (last 5 yr) -14.8%

 est. annual growth (next 5 yr) -5%
53

 Figure 2.18-3. Number of terrestrial licenses

 in the 3700-4200 MHz band.

 Figure 2.18-4. Number of satellite downlink licenses

 in the 3700-4200 MHz band.

Recent trends in number of assignments. Since reaching a peak in 1988, the number of assignments has

rapidly declined, as shown in Figure 2.18-3. Although the 4 GHz band was the most heavily-used band,

it is not particularly useful for new

assignments because of the difficulty in

coordinating around the satellite downlink

sites.

This band is shared with fixed-satellite downlinks, carrying primarily television with some

data and voice. The downlinks include satellite

terminals (licensed at their uplink frequency),

12,000 CATV (cable TV), 7,000 SMA (small

master antenna), and 2 million unlicensed

backyard TVRO (TV receive-only)

subscribers. Unlicensed TVRO downlinks are

not protected from interference. TVRO

subscribers decreased by 7% in 1998, mostly

switching to BSS [11].

Licensed downlinks (including about 75% of

the CATV and SMA installations), shown in

Figure 2.18-4, are protected against interference from terrestrial microwave links. Downlinks have very

small link margins, making them susceptible to even low levels of interference. Since many downlink sites

utilize the entire 3700-4200 MHz band and all points of the synchronous orbit, it is difficult to operate fixed

terrestrial transmitters near downlink sites at any frequency in the band. Although a new downlink site must

tolerate any interference it receives from

existing terrestrial links, it does not have to

accept any interference from transmitters

licensed in the future. Thus, new terrestrial

fixed links have been kept out of this band in

many urban locations (only 14 new terrestrial

licenses were issued in 1998).

Comments. There is wide variation between

the RBOCs in how this band is used. In some

areas, it is heavily used; in other areas it is

empty. Some areas are all digital; others still

have some analog modulation.

Estimated future growth trends. This band

has been reallocated to shared use by private

operators who want to use 20-MHz channels.

Because of the numerous downlink sites in

urban areas, it is unlikely that departing

stations can be easily replaced by new stations.

It is estimated that the terrestrial usage will continue to decrease by 5% annually over the next five years,

though the difficulty of licensing new systems will give operators a reason to hold on to existing licenses.

Unlicensed C-band TVRO operations will continue to lose subscribers to BSS.
 14The Federal Government has given up the 4940–4990 MHz part of this band to be reallocated to

non-Federal services.

54

4400-4990 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.19-1. Density of fixed assignments per square degree in the 4400-4990 MHz band.

Figure 2.19-2. Assignment density statistics.

2.19 Usage in the 4400-4990 MHz Band

Government Services14

Typical users. The 4400-4500 MHz band is Government exclusive and is allocated to fixed and mobile on

a primary basis. The 4500-4800 MHz band is shared with non-Government users. The Government has

primary allocations to fixed and mobile, and non-Government users have primary allocations to fixedsatellite. A footnote limits the fixed-satellite use to international intercontinental systems. The 4800-4990

MHz band is Government exclusive. Footnotes afford recognition of radio astronomy, and allocate space

research and earth exploration satellite services on a secondary basis. Geographical and statistical

assignment distributions are shown in Figures 2.19-1 and 2.19-2 and Table 2.19-1.

 Table 2.19-1. 4400-4990 MHz Band Statistics

 total US fixed assignments 1271

 maximum assignment density 53

 effective number of channels 49.5

 average US channel reuse 21

 peak reuse/1-degree block 1.1

 fixed growth rate (last 5 yr) 5.4%

 est. fixed growth (next 5 yr) 4%
55

 Figure 2.19-3. Number of licenses in the

 4400-4990 MHz band.

Military agencies are the primary users of this band. Uses include dual-purpose line-of-sight/troposcatter

links for tactical communications. These systems are transportable point-to-point systems, with sufficient

power (greater than 1 kW) to allow tropospheric scatter communications for beyond-line-of-sight links. In

addition, the band is used in drone control, target scoring, and balloon-to-ground data links for tethered

balloon surveillance. The average bandwidth for fixed systems is 10.9 MHz.

Air Force has 510 fixed assignments for training, remote relay of tactical radar data, and for miscellaneous

activities associated with electronic warfare. Army has 240 fixed assignments for training and for use on

test ranges. Navy has 180 fixed assignments for tactical training and for quality control test evaluation.

Justice has 240 fixed assignments, used for general communications and to connect sites providing mobile

services. The remaining assignments, held by civilian agencies and by non-Government entities, are for law

enforcement, antenna testing, data links for balloon surveillance, or aircraft data downlinks.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.19-3. Assignments in the 4400-4990 MHz band have grown from 943 in 1992 to 1226 in 1997, for an

average growth rate of 1%/year. In

September 1998, the GMF indicated there

were 1755 assignments in the band, of

which 1271 were fixed. A large number

of the listed military fixed assignments are

transportable terminals.

Comments. During the last five years, the

number of mobile assignments has

decreased substantially, while the number

of fixed assignments has increased.

The 4635-4660 MHz and 4660-4685 MHz

portions of this band were transferred to

the FCC for non-Federal use, beginning

in 1997 and 1994, respectively. The FCC

has allocated these bands to general fixed

and mobile services, but recently canceled

a scheduled auction of licenses in these

bands. The cancellation was said to be

caused by an apparent lack of commercial

demand for additional spectrum. In 1999,

NTIA requested the substitution of the

4940-4990 MHz band for the earlier frequency bands, to facilitate the deployment of the Cooperative

Engagement Capability (CEC), a major new mobile military communications system planned for much of

the remainder of the 4400-4940 MHz band.

Estimated future growth rate. We expect growth of fixed assignments in the band to remain around 4%

per year for the next 5 years, not counting any additional growth from non-Government systems in the

reallocated 50-MHz segment. The reallocation of 50 MHz of the band will result in existing Federal

assignments relocating into the remaining Federal segment.
 15This band was recently rechannelized and opened to use by private operators.

56

Figure 2.20-2. User bandwidths for

 the 5925-6425 MHz band.

5925-6425 MHz

Transmitters per 1 Degree Block

1 (32)

2 to 19 (357)

20 to 59 (285)

60 to 199 (185)

200 or More (10)

Figure 2.20-1. Density of Fixed licenses per square degree in the 5925-6425 MHz band.

2.20 Usage in the 5925-6425 MHz Band

Public and Private Operational Services15

Typical users. This band is used by the IXCs, LECs, alternative providers, and cellular companies. This

band provides 30-MHz channelization for long-haul, multiple DS-3 backbone routes, connections between

central offices, and between central offices and customer interface locations. It is also used extensively to

interconnect cellular sites. The band was recently opened to private operators and rechannelized for

bandwidths of approximately 0.4 MHz, 0.8 MHz, 1.6 MHz, 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, and

30 MHz, with an average bandwidth of 29.5 MHz. This band is shared with satellite uplinks, used for TV

and data. Geographical and statistical license information are shown in Figures 2.20-1 and Table 2.20-1.

Bandwidth information is shown in Figure 2.20-2.

 Table 2.20-1. 5925-6425 MHz Band Statistics

 total US licenses 33,569

maximum assignment density 338

 effective number of channels 17

 average US channel reuse 1975

 peak reuse/1-degree block 19.9

 annual growth rate (last 4 yr) 2.4%

 est. annual growth (next 5 yr) 3.0%
57

 Figure 2.20-3. Number of terrestrial licenses

 in the 5925-6425 MHz band.

Figure 2.20-4. Number of satellite uplink licenses

 in the 5925-6425 MHz band.

Recent trends in number of assignments. Population changes in this band over the past 11 years are

shown in Fig 2.20-3. Some of the changes shown

are real, but others are caused by the 10-year

industry-wide license renewal cycle. Licenses were

completely reissued in 1991, resulting in some

"deadwood" being weeded out. Deadwood develops

in the continually changing cellular industry when

users file new applications, but fail to promptly

eliminate the old ones. The magnitude of this effect

is unknown. Much growth in the past 6 years was

from migration from the 2 GHz and 4 GHz bands.

Substantial growth in 1997 was from private users

migrating from the 1.9 GHz band.

Comments. This band is the most active band for

traditional microwave systems, accounting for the

majority of new equipment licenses and the great

majority of sales dollars. Typically, high-capacity, multiple DS-3 systems are put in this band, while

narrowband systems are put in the 6.5 GHz band. In 1998, 5100 new licenses were coordinated in this band

and 1350 licenses were coordinated in the 6.5 MHz band. These 2 bands represent more than 75% of the

common carrier and private new license totals for bands 18 GHz and below. The number of microwave

links used to support cellular/PCS services may be larger than the 8% shown in Figure 2.20-3.

This band is shared with a large number of satellite

uplinks (Fig 2.20-4). These uplinks include a large

number of VSAT systems (probably 90 percent of

the total count), uplinks to TV networks, uplinks

intended for cable distribution, and many miscellaneous types of data and services. Since the uplinks are not bothered by the terrestrial transmitters,

and the terrestrial receivers have enough link

margin to tolerate substantial uplink interference,

this band has not suffered from the sharing problems that have occurred in the 4 GHz band. One of

the major VSAT operators moved operations from

this band to the Ku-band, resulting in a substantial

1992 decrease in licenses.

Estimated future growth trends. This band will

continue to be very heavily used for medium-tolong range telecommunication services, though

many microwave links continue to be replaced with fiber. PCS and cellular services will continue to use

this band to support rapidly changing system growth. There will be substantial growth caused by migration

from the 1.9 GHz and 2.1 GHz bands. This band is the lowest frequency licensed band generally available,

and it (plus the 6.5 GHz band) will be the chosen migration band for microwave users requiring long range

hops. On the other hand, many cellular/PCS users operate over shorter paths, and they may migrate to

higher frequency bands. A 3% net growth over the next 5 years is predicted. 
 16This band has been recently rechannelized and opened to use by common carriers.

58

Figure 2.21-2. Bandwidth of licenses in

 the 6525-6875 MHz band.

6525-6875 MHz

Transmitters per 1 Degree Block

1

2 to 19

20 to 59

60 to 199

200 or More

Figure 2.21-1. Density of licenses per square degree in the 6525-6875 MHz band.

2.21 Usage in the 6525-6875 MHz Band

Private Operational and Public Services16

Typical users. Typical users of this band include public safety, petroleum, railroads, and utilities, SCADA,

manufacturing, banking, and service providers. Until recently, this band had paired channels with

bandwidths of 800 kHz, 1.6 MHz, 5 MHz, and 10 MHz. The band was rechannelized in 1993 by adding

bandwidths of 400 kHz, 1.25 MHz, 2.5 MHz, and 3.75 MHz, in addition to allowing common carrier use

of the band. Average user bandwidth is 9.2 MHz. Geographical and statistical assignment distributions are

shown in Figure 2.21-1 and Table 2.21-1. Bandwidth information is shown in Figure 2.21-2.

 Table 2.21-1. 6525-6875 MHz Band Statistics 

 total US licenses 22,801

 maximum assignment density 309

 effective number of channels 38

 average US channel reuse 600

 peak reuse/1-degree block 8.1

 annual growth rate (last 5 yr) 5.4%

 est. annual growth (next 5 yr) 10%
59

Figure 2.21-3. Number of licenses in the 6525-6875 MHz band.

Recent trends in number of assignments. Growth in the 6.5 GHz band over the past five years has

averaged about 5.4%, as shown in Fig 2.21-3. In the few years immediately preceding 1992, the number

of private users in the band was quite stable. After 1992, the number of licenses increased rapidly, due

especially to migration from the

1.9 GHz band. The approximately 5000 private operational

licenses gained in this band since

1993 are roughly equal to the

5000 licenses lost from the 1850-

1990 MHz band over the same

time period.

In addition to the 19,446 private

licenses in 1997, Comsearch

records show 631 broadcast

auxiliary licenses, 574 noncellular common carrier assignments, and 739 cellular licenses.

Though the common carrier

assignments are not yet a large

percentage of the population of

the band, this is a growing part

of the band population. 

Comments. The FCC has

allocated this band as a migration

band for private systems forced out of the 1.9 GHz PCS bands (which has occurred in the last few years).

A similar (but larger) migration should be expected when 22,000 common carrier and private users are

migrated from the 2.1 GHz bands a few years from now, as described in Section 1.7. Common carriers and

private operations can use the band on a co-equal basis. This band and the nearby 6 GHz band are the

lowest-frequency fixed bands having a large number of narrowband channels suitable for cellular telephone

and SCADA applications.

Estimated future growth rate. Substantial new growth is expected from the remaining licensees displaced

from the 1.9 GHz and additional licensees from the 2.1 GHz Emerging Technologies' reallocation. A 10%

annual growth averaged over the next 5 years is predicted.
60

Figure 2.22-2. License density statistics.

6875-7125 MHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.22-1. Density of licenses per square degree in the 6875-7125 MHz band.

2.22 Usage in the 6875-7125 MHz Band

Broadcast Auxiliary, Public, and CARS (ENG-only) Services

Typical users. This band is allocated to broadcast auxiliary services, using NTSC frequency-modulation

on 25-MHz bandwidth channels. CARS is limited to mobile Cable TV pickup stations (similar to ENG).

The "7 GHz" band is channelized into 10 channels with 25-MHz bandwidth, though a substantial amount

of equipment operates in less bandwidth (typically 17 MHz). This band is the most heavily used band for

studio-to-transmitter links (STL), intercity relays (ICR), and electronic news gathering relay (ENG relay).

The band is also used for electronic news gathering (ENG), and for CATV pickup stations. TV translator

relay stations are also permitted on a secondary basis. Geographical and statistical assignment distributions

are shown in Figures 2.22-1 and 2.22-2 and Table 2.22-1.

Table 2.22-1. 6875-7125 MHz Band Statistics

 total US licenses 4586

maximum assignment density 92

 effective number of channels 10

 average US channel reuse 459

 peak reuse/1-degree block 9.2

 annual growth rate (last 5 yr) 5.8%

 est. annual growth (next 5 yr) 7.0%
61

Figure 2.22-3. Number of licenses in the

 6875-7125 MHz band.

Recent trends in number of assignments. Growth in this band over the past 11 years for broadcast

auxiliary and cable TV relay is shown in Figure 2.22-3. The recent growth is due to the need to support

additional local TV stations for ENG and

coverage of local events and, possibly, to

some early planning for HDTV and

related digital services.

Comments. This band may require

substantial adjustments to accommodate

the arrival of high definition television

(HDTV) and other compressed digital TV

formats, since many stations may need to

simultaneously support HDTV and NTSC

formats with STLs, ICRs, and ENGs.

Some major metropolitan areas

(Washington DC, New York, and Los

Angeles) have already begun to move a

large number of ICRs and STLs onto

fiber. The extensive use of fiber networks

to carry video programming during the

1996 Atlanta Olympics may be an

indication of future video transport

architectures.

Estimated future growth rate. The demand for fixed services in this band is still increasing steadily, and

the impending implementation of DTV broadcasting along with the increasing public appetite for video

entertainment could bring a sudden increase in the use of microwave links. This may be especially true if

many broadcasters put DTV antennas in different locations from the existing NTSC transmitters, requiring

support for two transmitter sites. However, if the DTV and NTSC transmitters are colocated, the use of

digital transmission technologies will allow simultaneous transmission of a 20-Mb/s DTV and a lightlycompressed (45 Mb/s with DS-3) NTSC signal within a single 25-MHz channel.

Since STL, ICR, and ENG relay are all fixed services, there is the potential to implement them with fiber.

It is difficult to predict when the economics of fiber vs. microwave will tip more strongly in the direction

of fiber. The presence of new shared DTV transmitting towers with multiple co-sited transmitters should

be a more tempting target for conversion to fiber. Conversion to fiber will also be encouraged by the

extensive optical fiber experience gained by cable TV companies and the increasing availability of wideband

fiber connections throughout many metropolitan areas.

Although the number of permanent fixed BAS microwave links is expected to decrease eventually, there

will continue to be strong use of the band for the next 5 years, possibly with a considerable 2-3 year growth

peak as DTV is implemented. An average 7% annual growth rate for the next 5 years is predicted.
62

7125-8500 MHz

Transmitters per 1 Degree Block

1

2 to 5

6 to 19

20 to 59

60 or More

Figure 2.23-1. Density of fixed assignments per square degree in the 7.125-8.5 GHz band.

Figure 2.23-2. Assignment density statistics.

2.23 Usage in the 7125-8500 MHz Band

Government Service

Typical users. The band is allocated exclusively to the Government from 7125-8450 MHz; from 8450-8500

MHz, it is shared with a non-Government primary allocation to space research. The Government primary

allocations are for fixed, space research, fixed-satellite, mobile-satellite, meteorological satellite, and earth

exploration satellite services in various portions of the band. Government fixed allocations are primary,

except for secondary status at 7250-7300 MHz and 7900-8025 MHz. Footnotes allocate space research to

a limited geographical area, earth exploration satellite service to non-Government users on a case-by-case

basis, and earth-to-space transmission in the space operations service on a limited basis. Additional

footnotes give military satellite service precedence by restricting fixed-satellite and mobile-satellite service

to military use. Average fixed bandwidth is 19.4 MHz. Geographical and statistical assignment distributions

are shown in Figures 2.23-1 and 2.23-2 and Table 2.23-1.

 Table 2.23-1. 7125-8500 MHz Band Statistics

 total US fixed assignments 8226

maximum assignment density 164

 effective number of channels 71

 average US channel reuse 124

 peak reuse/1-degree block 2.3

 fixed growth rate (last 6 yr) -0.3%

 est. fixed growth (next 5 yr) 0.0%
63

Figure 2.23-3. Number of assignments in the

 7125-8500 MHz band.

The FAA has 4,010 fixed assignments, including the radio communications link (RCL) system, a

nationwide network used to connect air traffic controllers with communications and radar data from remote

radar sites. The Air Force has 710 fixed assignments, used to support a large number of activities on

numerous test and training ranges. The Navy has 800 fixed assignments, used mainly in voice and data

links, ground forces communication, and land-line back up. The Army has 450 fixed assignments, used for

video scoring, closed circuit TV (security), point-to-point communications training, and for administrative

traffic.

DOE has 1,200 fixed assignments used for

system control and data acquisition

(SCADA) for electric power distribution

networks, perimeter security surveillance,

laboratory telecommunication systems, and

test site surveillance. Justice has 400 fixed

assignments, used for fixed backbone nets

used in law enforcement communications.

The Coast Guard has 160 fixed assignments,

used to relay maritime radar and

communications needed for safety and

navigation purposes in harbors and other

critical locations. TVA has 140 fixed

assignments, used for SCADA for electric

power distribution systems. 

In addition to fixed assignments, the bank is

used extensively for important military

space systems, such as the Defense Satellite

Communications systems (DSCS) and

LEASAT.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.23-3. Total assignments in the band have decreased slightly from 10181 in 1987 to 9,884 in 1997. Fixed

assignments have decreased slightly from 8300 in 1991 to 8149 in 1997.

The number of assignments in this band has remained stable over the past five years. Some military test

ranges have modernized their communications by installing fiber optics over parts of the ranges. The FAA

has recently modernized much of their radar microwave link (RML) system, replacing older analog links

with new digital RCL radios.

Comments. This is the Federal Government’s traditional point-to-point microwave band. Services typically

mirror the services provided by commercial providers, in areas or circumstances where commercial services

are not available. 

Estimated future growth rate. The Federal Government has always been directed to use commercial

services where possible. Continuously better availability of commercial services suggest that some agencyspecific microwave systems will be replaced with commercial services. Although this will not happen on

a wholesale basis, there may be a continuing erosion of systems in this band, which will be balanced by a

small number of new systems. In addition, some Federal systems may be moved into this band after being

displaced from the 1710-1755 MHz band by new non-Federal systems. The fixed usage in this band is

estimated to remain constant over the next 5 years.
64

10.55-10.68 GHz

Transmitters per 1 Degree Block

1 to 2

2 to 4

4 to 12

12 to 40

40 to 999

Figure 2.24-1. Density of licenses per square degree in the 10.55-10.68 GHz band.

Figure 2.24-2. License density statistics.

2.24 Usage in the 10.55-10.68 GHz Band

Public and Private Operational Services

Typical users. This band was previously allocated for Digital Electronic Message Service (DEMS), using

paired channels with either 2.5-MHz or 5-MHz bandwidths. DEMS systems are intended to transmit digital

information between an omnidirectional nodal station and multiple user stations with directional antennas.

DEMS stations were never widely used, however, and the band remained largely empty. This band also

has a few frequencies for point-to-point microwave stations with 1.25-MHz or 2.5-MHz bandwidth. In

1993, the band was reallocated to public and private fixed services, and rechannelized to add 400-kHz, 800-

kHz, 3.75-MHz, and 5-MHz channels (FCC, [3]). It is now heavily used by cellular operators, and average

user bandwidth is 2.9 MHz. Geographical and statistical assignment distributions are shown in Figures 2.24-

1 and 2.24-2 and Table 2.24-1.

Table 2.24-1. 10.55-10.68 GHz Band Statistics

 total US licenses 3657

 maximum assignment density 275

 effective number of channels 44

 average US channel reuse 83

 peak reuse/1-degree block 6.2

 annual growth rate (last 5 yr) 26.6%

 est. annual growth (next 5 yr) 12%
65

Figure 2.24-3. Number of licenses in the

 10.55-10.68 MHz band.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.24-3. Previous to 1993, these licenses were mostly associated with the non-DEMS point-to-point channels. When the band was reallocated to private and public point-to-point services and rechannelized for

popular bandwidths in 1993, it

began growing rapidly in support

of the cellular telephone base

stations. The earlier DEMS allocations have been deleted, but

existing DEMS assignments are

protected. This change has permitted very rapid growth in the

number of short-range, narrowband links deployed in support of

cellular sites.

Comments. This band is shared

with radio astronomy, which

causes the transmitter power levels

to be limited to lower values. 

Cellular and PCS operators will

continue to make extensive use of

this band, which is ideal for short,

narrowband cellular links. 

Estimated future growth rate.

The present rapid growth is

expected to continue for a few years. Near-term growth will be mostly in support of cellular and PCS

services; later growth will also support migration from 2 GHz. The average growth rate for the next 5 years

is expected to be 12% per year. 
 17This band has recently been rechannelized and opened to use by private operations.

66

Figure 2.25-2. User bandwidths for the

 10.7-11.7 GHz band.

10.7-11.7 GHz

Transmitters per 1 Degree Block

1

2 to 19

20 to 59

60 to 199

200 or More

Figure 2.25-1. Density of licenses per square degree in the 10.7-11.7 GHz band.

2.25 Usage in the 10.7-11.7 GHz Band

Public and Private Operational Services17

Typical users. This band is allocated to point-to-point service by common carriers, using 24 channels with

40-MHz bandwidth. The band is also used by common carriers providing relay of analog TV studio-totransmitter links. International fixed-satellite downlinks share the 10.95-11.2 GHz and 11.45-11.7 GHz

portions of the band. Recently, the band was opened to private users and rechannelized to add bandwidths

of 1.25 MHz, 2.5 MHz, 3.75 MHz, 5 MHz, 10 MHz, and 30 MHz. Current users have an average

bandwidth of 38.7 MHz, with only slight use of the narrower channelizations (Figure 2.25-2; note that 9008

common carrier licenses with a 40-MHz bandwidth have been omitted). Geographical and statistical

assignment distributions are shown in Figure 2.25-1

and Table 2.25-1.

 Table 2.25-1. 10.7-11.7 GHz Band Statistics

 total US licenses 11,172

maximum license density 385

 effective number of channels 25.8

 average US channel reuse 433

 peak reuse/1-degree block 14.9

 annual growth rate (last 5 yr) 3.2%

 est. annual growth (next 5 yr) -2.0%
67

Figure 2.25-3. Number of licenses in the

 10.7-11.7 MHz band.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.25-3. This band has been heavily used by the telephone companies to provide wideband links (up to three

DS-3) over moderate distances and was used heavily for early analog and digital telephone and analog

video. These wideband links are extensively used in urban areas and are routinely being replaced with fiber.

Recently, the band is being used by cellular operators when they require high-capacity links carrying a large

accumulation of traffic from multiple cellular sites.

This band closely matches the

growth pattern experienced in the

6 GHz common carrier band. It is

believed that the numbers are

influenced by the same 10-year

common carrier license renewal

cycle that ended February 1,

1991. The portion of the change

that is actual growth and how

much is caused by slow removal

of old licenses is not known.

Comments. This band was one of

the bands used heavily by

common carriers. It was used

especially in urban situations,

where the 4 GHz and 6 GHz

bands were already crowded and

the higher rain fading at 11 GHz

could be tolerated because of a

shorter path length. 

This band has been recently rechannelized to provide channel bandwidths of 1.25 MHz, 2.5 MHz, 3.75

MHz, 5 MHz, 10 MHz, 30 MHz, and 40 MHz. The 30-MHz channelization was added, since this is

sufficient for widely used links with a capacity of three DS-3 channels. In addition, private operation was

given a coequal primary allocation with common carrier operation, giving private users access to 30-MHz

and 40-MHz channels. The band is unique in providing very wide bandwidth channels at a relatively low

frequency, and it will continue to be used for high-capacity, moderate length circuits.

Estimated future growth rate. The use of this band by the local telephone companies will continue to

diminish as existing wideband common carrier microwave links are replaced with fiber. Although a few

narrowband systems displaced from the 2 GHz bands will move into the new narrowband channelizations

in this band, current use seems to suggest that this band will mainly be used by private users, LECs, and

CLECs needing access to 30-MHz and 40-MHz bandwidths. It is estimated that the use of this band will

decrease over the next 5 years at an average annual rate of 2 percent. 
68

Figure 2.26-2. License density statistics.

12.2-12.7 GHz

Transmitters per 1 Degree Block

1

2 to 3

4 to 11

12 to 39

40 or More

Figure 2.26-1. Density of licenses per square degree in the 12.2-12.7 GHz band.

2.26 Usage in the 12.2-12.7 GHz Band

Private Operational, International, and Broadcast Satellite Services

Typical users. Typical point-to-point users of this band include a variety of private users with 20-MHz

bandwidth. Average bandwidth is 18.2 kHz, including some 10 MHz channels. This band is now allocated

on a primary basis to broadcast satellite services (BSS), and existing terrestrial microwave users have had

only a secondary status since 1988. However, since no BSS service was implemented in the United States

for many years, many of the incumbent band users have been able to remain. Geographical and statistical

assignment distributions are shown in Figures 2.26-1 and 2.26-2 and Table 2.26-1.

 Table 2.26-1. 12.2-12.7 GHz Band Statistics

 total US assignments 813

maximum license density 58

 effective number of channels 27.5

 average US channel reuse 30

 peak reuse/1-degree block 2.1

 annual growth rate (last 5 yr) -7.0%

 est. annual growth (next 5 yr) -7.0%
69

Figure 2.26-3. Number of licenses in the

 12.2-12.7 MHz band.

Recent trends in number of assignments. The number of active microwave licenses in this band over the

past 11 years is shown in Figure 2.26-3. This band was allocated to broadcasting satellite service (BSS) in

1983, and point-to-point licenses are currently allowed only on a non-interfering basis.

Comments. This band was converted to BSS in 1983, but existing microwave users were "grandfathered"

until 1988, when they became secondary in status. Since there was no use of this band for BSS in the United

States, many microwave users have

chosen to continue existing

operations, but do not plan to upgrade equipment or add new licenses.

This situation left many unhappy

microwave users, because many users

went to considerable trouble and

expense to move out of the band (and

the ones who stayed were reduced to

secondary status), but for many years

no BSS systems ever used the vacated

spectrum. This history was recounted

often during discussions of the 2-GHz

Emerging Technologies reallocations.

BSS satellites were finally launched

and nationwide service was started in

1994. This service uses digital

compression techniques, powerful

satellite transmitters, and a 18" dish

consumer antenna to provide a

service that has been enthusiastically accepted by consumers. A million receivers were shipped within about

the first year of operation, and more than 7 million receivers were in operation by mid-1998. 

It seems likely that an increasing number of cases of interference to the growing number of BSS customers

will eventually force many remaining terrestrial fixed users in the band to cease operation, though this trend

does not yet seem to be underway. This surprising lack of interference may be partly due to the lack of

concentration of terrestrial microwave links or BSS customers in urban areas. (One of the major issues with

BSS operations is the right to provide distant network programming to urban and suburban customers who

live in neighborhoods where the local network broadcaster can be received.)

Estimated future growth rate. The number of fixed assignments in this band is estimated to decline

steadily (7% annual decrease) as old equipment is retired and a few of the remaining microwave links are

found to cause interference to BSS customers. 
70

Figure 2.27-2. License density statistics.

12.7-13.25 GHz

Transmitters per 1 Degree Block

1 to 9

10 to 99

100 to 299

300 to 999

1000 or More

Figure 2.27-1. Density of licenses per square degree in the 12.7-13.25 GHz band.

2.27 Usage in the 12.7-13.25 GHz Band

CARS, Broadcast Auxiliary, Private Operational, and Public Services

Typical users. This band is allocated to Cable Relay Systems (CARS) with four large blocks of 6-MHzwide channels (32-42 channels, depending on the block) and some 12.5-MHz channels. Broadcast auxiliary

service uses 25-MHz channels allocated in two groups offset from each other by 12.5 MHz. CARS

transmits amplitude-modulated blocks of NTSC-format TV channels from a central distribution point to a

cable head-end site (called a studio-to-headend link, SHL). Frequency-modulated systems using the 12.5-

MHz and 25-MHz channels provide studio-to-transmitter links (STL), electronic news gathering (ENG),

and intercity relay (ICR) for cable, broadcasters, and public operators. Public point-to-point stations are

allowed in the upper 50 MHz of the band. Average bandwidth is 6.88 MHz. Geographical and statistical

assignment distributions are shown in Figure 2.27-1 and Figure 2.27-2 and Table 2.27-1.

 Table 2.27-1. 12.7-13.25 GHz Band Statistics 

 total US licenses 123,170

 maximum license density 4389

 effective number of channels 80

 average US channel reuse 1540

 peak reuse/1-degree block 55

 annual growth rate (last 3 yr) -0.7%

 est. annual growth (next 5 yr) 0%
71

Figure 2.27-3. Number of licenses (in thousands)

 in the 12.7-13.25 GHz band.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.27-3. The very large number of licenses results partly from the counting of each 6-MHz channel as a

separate license, even though as many as 80 channels can be transmitted as a single block. The whole 80-

channel block could be transmitted from a single distribution point to as many as 15 cable head ends, using

a separate SHL point-to-point license for each destination and channel. Thus, as many as 1,200 licenses

could be used at a single site.

Although the number of CARS licenses

grew very rapidly to support a fastgrowing cable TV industry, the growth

almost stopped after 1991. Partly, this

was because construction on many cable

TV systems had been completed.

Mainly, however, after 1991, cable

system operators began installation of

optical fiber. Optical fiber presented two

major benefits: it provided an increase in

cable system bandwidth up to 750 MHz,

and it provided the potential for a twoway architecture that was not possible

with CARS. Depending on the details of

the individual cable system, CARS might

continue to be used for part of the signal

transport, or it might be completely

replaced by optical fiber. In some cases,

CARS was left in place as a backup

system. The resumption of CARS growth

for a single year in 1994 may have been

driven by the need to provide more signals to upgraded cable systems, as well as possible frustration with

progress towards the new multi-service cable architectures. In any case, many of the CARS licenses shown

in the figure are no longer actively used, having been replaced with optical fiber. More CARS links will

be abandoned as many remaining CATV systems are upgraded. 

In addition to the 123,170 CARS licenses, the Comsearch data base showed 694 cellular and 323 private

operational licenses at the end of 1997. Some of the private operational users migrated to this band when

the 12.2-12.7 GHz BSS band was cleared out.

Comments. The old one-way microwave CARS architecture will not easily support the more advanced twoway digital services like telephone and wideband Internet access that will be a major component in future

cable systems. Therefore, the future of CARS seems uncertain in its present form. The FCC has recently

granted permission for a private cable relay system being forced out of the 18 GHz band by new rules (see

Section 2.29) to operate in this band [12] .

This band allocation was revised in 1988 to include feeder uplinks for new mobile satellite services. The

uplink allocation includes the 13.0-13.15 GHz and 13.2-13.25 GHz bands.

Estimated future growth rates. No net CARS growth over the next 5 years is estimated. Rapid decreases

in CARS licenses may occur, depending on the progress in upgrading cable TV systems.
72

14.5-14.7145 & 15.1365-15.35 GHz

Transmitters per 1 Degree Block

1

2

3

4

5 or More

Figure 2.28-1. Density of fixed assignments in the 14.5-14.7145 GHz and 15.1365-15.35 GHz bands.

Figure 2.28-2. Assignment density statistics.

2.28 Usage in the 14.5-14.7145 GHz and 15.1365-15.35 GHz Bands

Government Service

Typical users. The 14.5-14.7145 GHz and 15.1365-15.35 GHz paired bands are allocated exclusively to

the Government for primary fixed Service and secondary Mobile and Space Research. Footnotes protect

Radio Astronomy in the band and provide secondary allocations to Passive Earth Exploration Satellite

service. Each subband is divided into 84 channels that are 2.5 MHz wide, with a corresponding channel

640 MHz away in the other subband. For applications requiring bandwidths in excess of 3.5 MHz, adjacent

channels in the frequency ranges 14.5-14.710 GHz and 15.14-15.35 GHz can be combined to obtain the

required bandwidth. For systems with emission bandwidths less than 3.5 MHz, the frequency bands 14.71-

14.7145 and 15.1365-15.14 GHz must be used. The average bandwidth for fixed systems in these bands

is 23.3 MHz. Geographical and statistical assignment distributions are shown in Figures 2.28-1 and 2.28-2

and Table 2.28-1.

 Table 2.28-1. 14.5-14.7145 GHz and

 15.1365-15.35 GHz Band Statistics 

 total US fixed assignments 473

 maximum assignment density 28

 effective number of channels 18.4

 average US channel reuse 25.7

 peak reuse/1-degree block 1.5

 fixed growth rate (last 5 yr) 6.2%

 est. annual growth (next 5 yr) 5%
73

Figure 2.28-3. Number of licenses in the 14.5-14.7145 GHz

 and 15.1365-15.35 GHz bands.

These bands are used for video data links in air traffic control, electronic warfare activities, experimental

research, and to transport administrative data. The Air Force has 190 fixed assignments, used mainly for

microwave data links and electronic warfare activities. The FAA has 175 fixed assignments which are used

mostly in Britescope links. The

remaining assignments are held by

10 agencies and are used in radio

system backbones, administration,

experimental research, or

supervision, control and protection

of electric power distribution

systems.

Recent trends in number of

assignments. Growth in these bands

over the past 11 years is shown in

Figure 2.28-3. Assignments have

grown from 566 in 1987 to 676 in

1997. The fixed assignments grew

from 309 in 1991 to 461 in 1997.

Comments. None. 

Estimated future growth rate. A

continued growth rate of 5% for

fixed assignments is estimated.
74

Figure 2.29-2. User bandwidths in the

 17.7-19.7 GHz band.

17.7-19.7 GHz

Transmitters per 1 Degree Block

1

2 to 19

20 to 59

60 to 199

200 or More

Figure 2.29-1. Density of licenses per square degree in the 17.7-19.7 GHz band.

2.29 Usage in the 17.7-19.7 GHz Band

Broadcast Auxiliary, CARS, Private Operational, and Public Services

Typical users. The "18-GHz" band is a general-purpose point-to-point microwave band, allocated for many

types of users sharing the band on a co-equal basis. Bandwidths of 2 MHz, 5 MHz, 6 MHz, 10 MHz, 12.5

MHz, 20 MHz, 40 MHz, 80 MHz, and 220 MHz are available with various channelization plans and

services. Services include STL, private, common carrier, CARS, and others. Average bandwidth of all

licenses is 7 MHz. Geographical and statistical assignment distributions are shown in Figure 2.29-1 and

Table 2.29-1, respectively. Bandwidth data is shown in Figure 2.29-2.

 Table 2.29-1. Statistics for the 17.7-19.7 GHz 

 Band (Including CARS and Private Cable) 

 total US assignments 98,967

 maximum license density 12,604

 effective number of channels 28.6

 average US channel reuse 3460

 peak reuse/1-degree block 441

 annual growth rate (last 5 yr),

 w/o private cable/CARS

 12.1%

 est. annual growth (next 5 yr)

 w/o private cable/CARS

 12%

DEMS services on five pairs of 10-MHz channels were recently transferred to the 24 GHz band. The 220-

MHz channelization was made for a very wideband microwave system, apparently made obsolete by fiber
75

Figure 2.29-3. Number of licenses in the 17.7-19.7 GHz

 band, excluding private cable and CARS.

and never deployed in the United States. Private cable relay provides for CARS-like transport of up to 72

TV channels, using contiguous 6-MHz channels in a single 432-MHz block at 18.142-18.576 GHz. It

supplies TV signals to private cable systems, typically in large hotel or apartment complexes. Like CARS,

private cable relay requires a separate license for each TV channel and each receiving destination,

producing as many as 2000 licenses at a single hub transmitter site (72 channels to each of 30 buildings).

Recent trends in number of assignments. Growth in this band is shown in Figure 2.29-3, which omits

licenses for private cable relay and CARS. Common carrier use of this band has grown rapidly (22%

annually over the last 5 years). Private use of this band has been growing at a moderate rate (4% over the

last 5 years). The use of conventional private microwave was estimated separately from private cable/CARS

in 1992 and 1993 by assuming uniform growth for conventional private microwave services.

The private cable (not included in

Figure 2.29-3) has shown extraordinary growth. Since private

cable serves independent building

complexes, it has not developed an

interconnecting optical fiber system

like cable did. Assuming that the

estimates for conventional private

microwave service are correct, private

cable grew as follows:

Year Private Cable licenses

1991 -none1992 7435

1993 10542

1994 24314

1995 54694

1996 65940

1997 84825

Comments. DTS/DEMS services were

permitted in this band, but never extensively used. Recently, a large number of DEMS licenses were issued

to provide wireless local loop services. However, analysis showed that the cumulative effect of a large

number of DEMS systems could interfere with existing and proposed satellite systems. Therefore, all

DEMS licenses have been moved out of this band and placed into the 24 GHz band (see Section 2.31).

Direct broadcast satellite service (BSS) shares the 17.3-17.8 GHz portion of this band for uplink functions.

This band is also shared with Ka-band satellite downlinks. A recent FCC NPRM proposed making

terrestrial use primary in 17.7-18.3 GHz, GSO/FSS service primary in 18.3-18.55 GHz, NGSO/FSS and

terrestrial services co-primary in 18.55-18.8 GHz, NGSO/FSS primary in 18.8-19.3, and MSS feeder and

terrestrial use co-primary in 19.3-19.7 GHz. Terrestrial use is “grandfathered” in secondary bands[13]. 

Estimated future growth rate. Common carrier use of this band is estimated to continue growing at an

annual rate of 15% for the next 5 years, used mostly for shorter links (less than 20 km). Private cable may

continue its rapid growth, but this will depend on rapidly changing business, regulatory, and technical

factors that are difficult to predict. Private operational use will grow 2% annually over the next 5 years.
76

Figure 2.30-2. License density statistics.

21.2-23.6 GHz

Transmitters per 1 Degree Block

1

2 to 19

20 to 59

60 to 199

200 or More

Figure 2.30-1. Density of licenses per square degree in the 21.2-23.6 GHz band.

2.30 Usage in the 21.2-23.6 GHz Band

Government, Private Operational, and Public Services

Typical users. The "23 GHz" band is a general-purpose point-to-point band shared by private, common

carrier, and Federal users. The band is channelized at 50 MHz, with a maximum bandwidth of 100 MHz.

Alternate 600-MHz portions are set aside for common carrier and private operational users, with

Government use across the entire 2.4 GHz. Almost all users use an entire 50 MHz channel. The license data

for common carrier and private service come from the Comsearch databases; the Federal assignment count

comes from the GMF. Geographical and statistical assignment distributions are shown in Figures 2.30-1

and 2.30-2 and Table 2.30-1.

 Table 2.30-1. 21.2-23.6 GHz Band Statistics

 

 total US assignments 11,020

 maximum assignment density 435

 effective number of channels 48

 average US channel reuse 230

 peak reuse/1-degree block 9.1

 annual growth rate (last 4 yr) 6.6%

 est. annual growth (next 5 yr) 4%

The major Federal users include the Navy (350 assignments), Army (330), Air Force (310), Agriculture

(200), and Energy (105). Government uses include video links for security and safety monitoring, video

weather maps and data, and general voice and data applications.
77

Figure 2.30-3. Number of licenses in

 the 21.2-23.6 GHz band.

Recent trends in number of assignments. Growth in this band over the past 11 years is shown in Figure

2.30-3. The rapid growth rate of the early years seems to be slowing somewhat, though we believe that

moderate growth will continue. 

Comments: This band is one of the newer bands in terms of the availability of popular equipment. At one

time this band was hailed as the band that would make bypass of the LECs possible, and huge growth was

forecast. This huge growth did

not occur, but the band is experiencing steady growth now. A

wide variety of equipment is

available, including some fairly

inexpensive equipment that has

the transmitter or receiver

integrated with the antenna. Much

of the equipment uses only simple

frequency modulation, depending

on the wideband channelization to

obtain high data rates, instead of

complex QAM modulations

giving multiple bits per sample.

The resulting package is smaller

than many systems operating at

lower frequencies, allowing

operation from an office window

and eliminating rooftop antenna

rent. 

This band suffers additional (and

variable) signal attenuation from

water vapor, which limits its use to relatively short path lengths, even compared to some higher frequency

bands. In addition, no narrowband channelization is available, so there is often poor matching between

narrowband applications and the available channelization. Unlike many other bands, there is no bandwidth

conservation criterion that requires a minimum data rate/bandwidth ratio. Although common carrier services

make some use of this band, almost no cellular use was reported. 

Estimated future growth rate. Although the huge growth once forecast for this band has not materialized,

an average of 4%/year growth rate is expected for the next 5 years. This growth will be broadly distributed

over a number of short-range services.
78

2.31 Usage in the 24.2-24.45 and 25.05-25.25 GHz Bands

Public Service

Typical users. The “24 GHz band” (24.25-24.45 GHz and 25.05-25.25 GHz) was reallocated in March

1997 for use by digital electronic message service (DEMS). The band is allocated as five pairs of 40-MHz

channels, with respective paired channels separated by 800 MHz. These channels will be allocated by

Economic Areas (EA’s). The licensee will be expected to divide the frequency bands and geographical

areas into smaller pieces, as required for the technical details of the system to be implemented. In addition,

unlimited aggregation or disaggregation of frequencies and geographical areas will be permitted between

various licensees.

Comments. Wireless local loop (WLL) services in this band began as digital electronic message services

(DEMS) moved from the 18 GHz band. Although DEMS had been barely used for many years in the 18

GHz band, recently it had been identified as a practical means of providing WLL services and considerable

expansion of DEMS was planned. A closer inspection of DEMS in the 18 GHz band, however, exposed

the possibility of interference to some existing and planned 18 GHz satellite systems. The problem was

solved by moving DEMS from 18 GHz to a new (previously Federal) band near 24 GHz. 

Teligent Corp has most of the licenses in this band and has announced that it will provide WLL services

in 30 major metropolitan areas by the end of 1999. This service will be based on a point-to-point or pointto-multipoint architecture that will provide fixed wireless access to commercial businesses, typically with

T1 or multiple T1 services.

Estimate of future growth. We believe that growth in this band will be rapid over the next 5 years, as

Teligent is aggressively developing systems in many major US cities. However, this service will be

competing head-on with other new HDFS services at 28 GHz (LMDS) and 39 GHz (wireless fiber); the

eventual outcome of this competition cannot be predicted with any certainty.

2.32 Usage in the 25.525-27.5 GHz Band

Government Service

Typical users. This Federal Government band is virtually unused by the fixed services, having a total of

20 developmental and experimental fixed assignments belonging to the Army and Justice. However, NASA

is planning to build the next generation of its TDRSS data relay satellites in this band.

Comments. No commercial systems have been installed in the band.

Estimate of future growth. This band will probably grow substantially in the future. However, it is not

clear which services will be allocated to this band by the time that growth occurs. 

2.33 Usage in the 27.5-31.3 GHz Band

Public Service (LMDS)

Typical users. This band was auctioned in March 1998 for about $580 million for the purpose of providing

local multipoint distribution service (LMDS). Although no large scale deployment has begun yet,

CellularVision has been using 15 transmitters in the New York City area to provide Internet access and TV
79

to 18,000 customers. 

Comments. The auction divided the band into Block A and Block B subbands in 493 Basic Trading Areas

(BTA’s) across the United States. The Block A licenses provide 1150 MHz of spectrum (27.5-28.35 GHz,

29.1-29.25 GHz and 31.075-31.225 GHz). The Block B licenses provide 150 MHz of spectrum (31.0-31.075

GHz and 31.225-31.3 GHz). Earlier planning for this band had suggested point-to-multipoint one-way

distribution of analog TV using multiple short-range (up to 3 miles in range) line-of-sight transmitters,

giving the service the name “cellular cable.” A small (6" diameter) highly-directional customer antenna

would select the best-positioned transmitting site and overcome some of the path loss. More recent planning

suggests that the service will be two-way digital, providing a full range of telecommunications

services–including wideband Internet access, telephone, compressed digital TV, etc. The relatively short

range and use of directional antennas would permit a large degree of frequency reuse and higher

bandwidths to each user.

Estimate of future growth. The use of this band is expected to expand rapidly, especially in the near

future, as auction winners build out infrastructure in most major metropolitan areas in the next few years.

However, because this service will be competing head-on with other new HDFS services at 24 GHz (WLL)

and 39 GHz (wireless fiber), as well as broadband digital cable services and LEC ADSL, the outcome of

this competition cannot be predicted with any certainty.

2.34 Usage in the 38.6-40.0 GHz Band

Public and Private Services

39 GHz band. The 39 GHz band (38.6-40.0 GHz) is proposed to be allocated for a wide variety of

services, including terrestrial point-to-point, point-to-multipoint, and (possibly) mobile services. The

allocation for this band is currently established under Memorandum Opinion and Order FCC 99-179,

adopted in July 1999. The band is available for use by common carrier and private users, and plans are

being made to auction the band by dividing the United States into 172 Economic Areas (EAs) and 3 EA-like

areas outside the continental U.S. Early uses of the band are expected to include interconnection of cellular

and PCS sites, bypassing incumbent LECs and connecting business customers directly to competitive LEC

switches, and wireless local loop service to individual consumers. 

The 39 GHz band is channelized in 14 pairs of 50-MHz blocks, with corresponding paired blocks separated

by 700 MHz. Permission was granted to early licensees to use a given pair of 50-MHz blocks over a selfdeclared rectangular geographical area, though licenses awarded by auctions will be divided geographically

into EAs and unpaired 50-MHz bands. It is expected that a user will subdivide the 50-MHz bands into

smaller channels and areas, suitable for a cellular-like frequency reuse architecture. Users will be

responsible for their own internal frequency coordination, as well as selection of technologies, bandwidths,

modulation, antenna performance, etc. Fixed point-to-point and point-to-multipoint operation is permitted.

Coordination between users will be required for sites within 16 km of geographical boundaries on cochannel and adjacent channel frequencies, though no specific power flux density limits have been set for

signal leakage across boundaries. Existing blocks can be subdivided or aggregated on a geographical or

frequency basis and sublicensed to other users. Licenses for three pairs of frequency blocks will be

auctioned at one time, resulting in four independent auctions, with the first auction planned near the end of

1999. Note that the 39.5-40.0 GHz subband is also allocated for Federal satellite operations.

Winstar Corporation is a major user in this band, providing fixed microwave links to bypass the incumbent

LECs and to provide wideband links to urban locations where optical fiber is not yet available (a service
80

that Winstar calls “wireless fiber”). A typical Winstar deployment strategy is to place fiber- or

microwave-connected switches in several tall buildings located several miles apart. From these hub

buildings, directional 39-GHz point-to-point links or segmented point-to-multipoint links are set up to many

buildings within a several-mile radius. It is claimed that this strategy can provide wideband connections to

many business customers more rapidly and more economically than wireline or fiber alternatives. The 39-

GHz links are limited to relatively short, line-of-sight applications because of precipitation-related path loss.

On the other hand, the high frequency band permits the use of many small, high-performance antennas

giving enhanced frequency reuse.

2.35 Other Frequency Bands of Interest

This section mentions additional selected bands with existing or proposed fixed allocations, or allocations

which would permit their use to provide services similar to fixed services. These selected bands do not

include all of the additional bands with fixed or “similar-to-fixed” allocations. 

2.1 GHz band. The 2110-2150 MHz band is being created from half of the existing paired common carrier

and private operational fixed service bands. The licenses in this band will be auctioned, and the new

licensees will be required to reimburse the incumbent fixed service users for the expense of moving to a

new band. 

2.3 GHz band (WCS). The wireless communication service (WCS) bands are 2305-2320 MHz and 2345-

2360 MHz. The intervening 2320-2345 MHz band is allocated for the digital audio radio service (DARS).

The WCS band was auctioned in April 1997 for about $15 million. It was licensed as paired 5-MHz

subbands over 52 major economic areas (MEAs) or 12 regional economic areas (REAs). The WCS bands

are allocated for a broad range of fixed and mobile wireless applications under Part 27 rules. At present,

there has been little implementation of systems in this band, though several applications have been

proposed. Some licensees have proposed using the band to extend the DARS service. Others have proposed

fixed point-to-point services, WLL, or using the band as the reverse channel for an expanded two-way

digital MMDS system. 

3.65-3.7 GHz band. This band was released by the Federal government under the requirements of the 1993

Omnibus Budget Reconciliation Act. It was allocated to non-government Fixed services by FCC 98-337,

an NPRM released December 1998. The NPRM suggests that this band would be especially suitable for

WLL and fixed wireless access (FWA). Existing Military radars are grandfathered at three U.S. sites and

high-power airborne radars remain in adjacent bands.. Frequencies in 3.4-3.7 GHz range are expected to

be used for WLL in many countries (including Mexico).

4.9 GHz band (GWCS). The general wireless communication service (GWCS) bands include 50 MHz

of Federal spectrum in the 4400-4990 MHz band, to be licensed via auction by the FCC. The 50 MHz of

spectrum originally included the 4635-4660 MHz and 4660-4685 MHz bands. Although these bands were

scheduled to be auctioned, the FCC postponed the auction because of an apparent lack of interested bidders.

Recently, NTIA requested that the previous bands near 4.6 GHz be exchanged for the 4940-4990 MHz

band. Licenses in this new band will presumably be auctioned in the near future for a wide range of

wireless services, though no details are available yet.

5 GHz U-NII band. The unlicensed national information infrastructure (U-NII) band includes the 5.150-

5.350 GHz and 5.725-5.825 GHz frequency bands. A wide range of unlicensed applications is permitted,

including point-to-point and point-to-multipoint uses. Permissible transmitter power is proportional to

bandwidth (up to a 50-MHz maximum bandwidth), with the expectation that this service will be used only
81

for wideband data transmission, such as wireless LANs. Note that the 5.725-5.825 GHz band overlaps the

5.8 GHz ISM band, however, and narrowband devices could use this spectrum under the unlicensed Part

15/ISM rules.

37 GHz, 42 GHz, and 43 GHz bands. The 37-38.6 GHz band has shared Federal and non-Federal

primary allocations for fixed and mobile services. The FCC has allocated the 41.5-42.5 GHz band for

primary fixed and mobile services (suitable for general wireless services) The 42.5-43.5 GHz band has

primary allocations for Federal fixed and mobile operations[14]. The 43 GHz band and 47 GHz band (see

next paragraph) had initially been allocated to shared Federal and non-Federal operation, but were later

reallocated to exclusive Federal and non-Federal services, respectively, to simplify management of those

bands. Though details on all of these bands are not yet available, it is assumed that the ubiquitous wireless

services that will use these bands will not necessarily be compatible with various satellite services.

Therefore, frequency bands recently allocated in this general frequency range have been given primary

allocations for terrestrial use or satellite use, but not both services in the same frequency band. These

bands might also be used in conjunction with the 39 GHz band (Section 2.34).

47 GHz band. The FCC has established the 47.2-48.2 GHz band for exclusive non-Federal fixed point-tomultipoint services, including services delivered via stratospheric platforms–also called high altitude

platform systems (HAPS) [15]. Though the rules have not been completed yet, it has been proposed that

the rules will be optimized for stratospheric platforms, while permitting a wide range of other services.

The band will include three 100-MHz paired blocks, with each 100-MHz block in the lower half of the band

paired with a corresponding block 700 MHz higher in frequency. These paired blocks will be licensed by

large geographical areas (12 regional economic area groupings–REAGs) to users via auctions (date not set

yet). The users are expected to break the blocks apart (or aggregate them) as needed for particular

applications. 

Sky Station International, Inc. was the first to propose that this band be used for “stratospheric satellites.”

These helium-filled high-altitude airships would permanently float 100,000 ft above major metropolitan

areas, using large arrays of photovoltaic cells and active station-keeping to relay many types of data

throughout a large metropolitan area. This concept combines many of the best telecommunication

advantages of geostationary satellites and high terrestrial relay towers. However, there are substantial

vehicle engineering challenges, and the feasibility of such platforms remains to be demonstrated. Other

developers have proposed similar services using relay teams of long-duration high-flying aircraft or

continuously-aloft solar-powered high-flying aircraft. The FCC has noted stratospheric satellites as the

expected use of the 47 GHz band, but has not reserved any frequencies exclusively for this purpose.

59-64 GHz band. Signals in this band experience a 15-20 dB/km attenuation, caused by absorption by

oxygen in the air. The FCC has established the 59-64 GHz band as a general-purpose unlicensed band under

Part 15 rules, partly since the oxygen absorption will ensure that signals will rapidly decrease with distance,

minimizing the possibility of interference. Users in this band must transmit a coded ID that will identify

themselves, at least as often as once every second, as an aid to rapidly resolving any interference problems.

In addition, the 59.00-59.05 GHz portion of the band is to be used in common by all users to assist in

coordinating the real time use in the remainder of the band. Although there are no users in this band yet,

the 5 GHz of total bandwidth and the ability to use directional antennas suggests that the band will be used

for short-range, wide bandwidth, point-to-point links and omnidirectional WLAN applications. 

Higher frequency bands. The recent allocations of the 47 GHz and 59-64 GHz bands are part of a larger

FCC proposal to allow commercial use of a series of frequency bands extending up to 153 GHz (ET Docket

No. 94-124 [16]). In general, the rules proposed for these bands are quite flexible, partly because the very

high frequencies do not permit long-range propagation, reducing the potential for interference between
82

users. Twelve frequency bands between 40 GHz and 153 GHz with a total of 18 GHz of spectrum are

defined for a mix of licensed millimeter wave service (LMWS) and unlicensed Part 15 service.

 Licensed bands Unlicensed bands (Part 15) 

40.5-42.5 GHz 47.2-48.2 GHz 59-64 GHz - - - -

71.0-71.5 GHz 84.0-84.5 GHz 71.5 -72.0 GHz 84.5-85.0 GHz

103.0-103.5 GHz 116.0-116.5 GHz 103.5-104.0 GHz 116.5-117.0 GHz

122.0-122.5 GHz 126.0-126.5 GHz 122.5-123.0 GHz 126.5-127.0 GHz

152.0-152.5 GHz - - - - 152.5-153.0 GHz - - - - 

The Part 15 service would allow low power unlicensed operation for a wide range of services. The licensed

operation is proposed to be licensed to a very general LMWS in larger frequency blocks over large

geographical areas (Major Trading Areas—MTAs). The FCC will continue to define the specific rules for

each of these bands over the next several years. 

Few of these bands have any commercial use yet; most bands have no users. Presumably, the lack of

current users is caused by lack of economical electronic semiconductor devices as well as special

challenges of system design. However, these bands will not remain unused for long. Automotive

manufacturers are working on short-range radar sensors in the 76-77 GHz band, and at least one cellular

equipment supplier has mentioned the use of the 57-59 GHz band to link sites together. 

3. COMPARISON OF PREDICTIONS WITH LICENSE DATA 

The 1993 Staff Study on the fixed services predicted specific changes in the number of licenses in various

frequency bands and fixed services. One purpose of the current study is to review the accuracy of the

earlier predictions and to understand why deviations occurred. We are interested mainly in the major

features of this comparison; minor deviations from predictions will be ignored. The following sections

compare earlier 5-year license predictions with license data over the past 6 years.

The 1993 staff study made predictions based on the number of licenses issued (or assignments, in Federal

bands) as a means of tracking the growth in the use of microwave fixed services. Although counting

licenses may still be the best single indicator of activity, it surely seems to tell a diminishing part of the

whole story. The increasing degree of flexibility in the use of individual frequency bands (multiple types

of users, multiple services, multiple bandwidths) presents the danger of an “apples versus oranges”

comparison, and the increasing number of transmitters that do not need to be individually licensed brings

the probability of “blind spots” where large numbers of transmitters are missed.

3.1 Federal Government Service

The 1993 Staff Study estimated that the total average growth rate for the Federal bands would be 0.3% net

increase per year for the next 5 years (Matheson [1], Table 4.2-3). Figure 3.1 shows the total number of

assignments in the Federal bands, with the fixed assignments identified for the last 7 years. The breakdown

between fixed and other services was not available in all bands, and some information was based on

estimates. 
83

Figure 3.1. Total Federal assignments in fixed bands.

 Figure 3.2. Total private licenses in the bands above 1 GHz (w/o CARS/PC).

The numbers of identifiable fixed

assignments in the Federal bands were:

1991 - 28069

1992 - 28871

1993 - 29084

1994 - 29350

1995 - 30008

1996 - 30736

1997 - 30564

This gives an actual average annual

growth for fixed services in the last six

years of 1.4%. It should be noted that

most of the growth between 1991 and

1992 was due to more than 800

assignments that were added for

transportable terminals, as the result of a

policy decision to individually license

some of these systems. If this “paper

growth" is subtracted out, the average

annual growth in number of assignments

was about 1%.

3.2 Private Operations Service

The total growth rate for the private operations services was estimated to be an increase of 3.2 percent a

year (Matheson [1],

Table 4.2-6). Figure

3.2 summarizes the

number of licenses in

the private services.

The “Misc.”

category includes

private license counts

from the 2.4 GHz, 6

GHz, 10.5 GHz, 11

GHz, and 13 GHz

bands. Most of these

bands have small

numbers of licenses,

and many of them

were only recently

opened to private

uses. The data in

Figure 3.2 omits the

18-GHz private cable service, a service similar to CARS, that added more than 75,000 licenses over the

last five years. Since the private cable service is quite different from traditional private services and quite

similar to CARS, these licenses have been included with CARS (Section 3.5).
84

 Figure 3.3. Total common carrier licenses in the bands above 1 GHz.

In general, the private services grew approximately as predicted, with the forced migration from the 1.9

GHz band pushing some growth into the 6.5 GHz band and some of the higher frequency bands. Overall,

the private services grew at a 1.2% annual rate between 1991 and 1994, driven mainly by the need for new

licenses to provide a destination for users who would soon be displaced from the 2 GHz PCS bands. Licenses decreased at an annual rate of 1.6% between 1994 and 1997. This decrease was driven almost

entirely by the decrease of users in the 1.9 GHz band, as those users were displaced by new PCS systems.

Although the high level of license activity due to the 1.9 GHz migration has mostly disappeared, there were

still about 1750 new private licenses coordinated in 1998.

3.3 Public Services (Common Carrier) Bands

The 1993 staff study predicted a decrease of 6% per year in the total number of common carrier licenses

(Matheson [1], Table 4.4-2). Figure 3.3 shows the total common carrier licenses for bands above 1 GHz.

The “Misc.” bands include 6.5 GHz, 13 GHz, and 23 GHz—all of which have relatively small numbers

of common carrier licenses. This graph shows 1991 and 1997 totals of 68,375 and 74,759, respectively.

This is an increase of 6384 licenses, representing an actual annual increase of 1.5%. This is a major

systematic deviation

from what was

estimated.

One might, in fairness,

suggest that all of the

data before 1992

pointed to the earlier

conclusion. Long-term

trends were consistently

and strongly downward, and there was a

good basis of

understanding for those

results. Our current

understanding of what

happened is as follows:

1. The telephone system continues to switch from microwave to fiber for long-distance and local connections. This trend is aided by numerous competitive fiber providers, especially in urban areas.

2. In the 1991-1994 period there was a major movement of systems from the 4 GHz band to the 6 GHz

band, due to worsening problems in the 4 GHz band in coordinating with numerous satellite downlink

stations. These coordination problems made it easier to place new links or any required 4 GHz system

updates into the 6 GHz band. This would have been particularly easy to accomplish in some cases since the

original 4 GHz hardware was also designed to operate at 6 GHz, and similar propagation characteristics in

both bands generally meant that no path re-engineering was needed. Thus, many 4 GHz paths were switched

to the 6 GHz band. Simultaneous with the shift from 4 GHz to 6 GHz, there was an overall long term

decrease in the total number of licenses in the combined bands of about 4% per year.

The 4 GHz common carrier band declined faster than predicted, then hit a plateau around 12,000 licenses.

Recent NTIA spectrum monitoring measurements in selected geographical regions [17][18][19] show the
85

band almost completely devoid of terrestrial use, so the license data may indicate users temporarily holding

unused licenses or keeping microwave networks “just in case,” rather than indicating actual use. 

3. All common-carrier licenses were renewed on February 1, 1991. In a normal year, a portion of

abandoned licenses remain in the records for a while until they are deleted. The dip in licenses in 1991 was

caused partly by carriers updating their license applications, as required, in preparation for the beginning

of a new 10-year license cycle. Thus, the 1991 dip in licenses was partly caused by clearing out previously

abandoned licenses. This cycle shows up particularly in the 6 GHz and 11 GHz bands.

The problem with abandoned licenses is caused when a station is moved or re-aimed. A license is needed

before the new configuration is implemented, but cancellation of the old license is not necessarily performed

immediately. This problem will be worse in bands where there are many changes in network configuration,

since a single station may generate an additional set of abandoned licenses every time that a site is

reconfigured.

4. The cellular/PCS industry is still growing very rapidly. This growth is not merely an expansion on the

periphery of an established service area, but growth is distributed throughout the system. The addition of

more down-sized internal cells typically requires multiple microwave changes. These changes include

reconfiguration of network topology, but they may also require adding more capacity to existing paths. The

2 GHz band and 10.5 GHz band were used to connect individual cellular sites with low capacity links, while

the 6 GHz and 11 GHz bands were used to provide wideband backbone for cellular systems. This provided

very strong growth in the 2 GHz , 6 GHz, and 10.5 GHz bands and moderate growth in the 11 GHz and

18 GHz bands, partially compensating for licenses lost in the shift to fiber. 

One should observe that a lower percentage of cellular sites are apparently using microwave connections

than in the past. With 50,000 base stations at the end of 1997, the cellular/PCS industry was identified as

using only 15,000 microwave links. Although we believe that we are underestimating the number of

microwave licenses used by the cellular industry, these numbers show far less than 70% of sites connected

by microwave (an estimated percentage from early days of the cellular industry). Assuming a minimum of

2 licenses per site, 70% microwave usage would require 70,000 licenses–which is almost equal to the total

number of all common carrier licenses (about 75,000).

The apparent “plateauing” of the number of common carrier licenses should not be mistaken for a lack of

activity in the bands. In 1998, for example, some 6100 new common carrier licenses were coordinated,

representing an annual “churn” of about 9% of the total number of existing licenses. The great majority of

these new licenses were issued in the 6 GHz band (almost 4500 new licenses), representing a 14% churn

rate in this band. This high level of activity is consistent with microwave systems being used especially to

connect new or expanded activities, but later many of these microwave links are replaced with optical fiber

or other technology whenever these technologies become locally and inexpensively available. On the other

hand, only 14 new licenses were coordinated in the 4 GHz band, illustrating the extent of the problems in

sharing this band with satellite downlinks. 

3.4 Broadcast Auxiliary Service

The 1993 staff study estimated an average annual increase of 10% in the broadcast auxiliary services

(Matheson [1], Table 4.5.3). Figure 3.4 shows the growth in the number of licenses for broadcast auxiliary

services. Between 1991 (4923 licenses) and 1997 (8483 licenses), the number of licenses increased by 3560,

giving an actual average annual percentage increase of about 9.5%, very close to the earlier estimate.
86

Figure 3.4. Total broadcast auxiliary licences

 in fixed bands above 1 GHz.

 Figure 3.5. Total CARS and private cable licenses.

The growth during this period was controlled by

two opposing trends. The television and cable

industry has been growing fairly rapidly, adding

whole new networks to supply programming to

an increasing number of cable and broadcast

chan-nels. On the other hand, the switch to

digital TV (DTV) has taken longer than

originally anticipated, and the details of the

required changes have not been completely clear.

During this period, many TV stations may have

been reluctant to buy new BAS transmission

equipment that would possibly be made obsolete

during the switch to DTV. 

3.5 Cable TV Relay Service (CARS) and Private Cable

The 1993 staff study predicted that the 13 GHz CARS band would decrease 5% per year, averaged over

the next 5 years (Matheson [1], Table 4.6-3). A more qualitative statement was that the rapid growth in this

band would stop; then licenses would decrease as existing video traffic moved from CARS systems to

optical fiber.

Figure 3.5 shows the license count for the 13 GHz CARS band and the private cable and CARS service in

the 18 GHz band. Since these two services are technically very similar (though provided to slightly different

customers), they were combined for analysis

purposes. The 1991 data (107,402 licenses)

and 1997 data (207,995 licenses) give an

actual increase of 100,593 licenses or about

12% annual increase. These numbers show

that the earlier rapid growth in the 13 GHz

band paused for several years (1991-1993),

then grew a little for a single year in 1994,

and has decreased slightly since then. The

number of licenses in the 18 GHz band, on

the other hand, began growing rapidly in

1992 and has continued very rapid growth. 

CARS and private cable microwave are

technically and functionally almost identical,

but they are controlled by different

regulations, which has caused them to

develop in vastly different directions. CARS

was developed in the 13 GHz band to efficiently move large blocks of 6-MHz TV
87

channels between a program origination point (typically a satellite downlink site) and the cable system

“headend” sites. A similar block of contiguous 6-MHz channels was also created in the 18 GHz band for

use by CARS or private cable operators. CATV headends convert the CARS signal to a signal in the cable,

and the signal is transferred through an elaborate network of cables, amplifiers, and splitters to individual

customers (usually private homes or apartments). CARS is considered part of the CATV system, whose

cable connections spread across every public roadway where houses are built. 

Beginning around 1991, CATV operators began “remodeling” their cable networks to allow more channels

and future digital services. This remodeling broke up the single coaxial network into many smaller coaxial

networks (typically each covering1000 homes) connected together with optical fiber. The smaller coaxial

networks allowed an expansion of system bandwidth from around 300 MHz to as much as 750 MHz,

providing more channels and the possibility of individualized two-way services to each customer. Initially,

the remodeling was used mainly for additional TV channels, but recently many cable systems have begun

to offer a wide variety of two-way digital services, including digital TV channels, high-speed cable

modems, and telephony. The proposed AT&T/TCI merger is aimed directly at large-scale implementation

of two-way digital cable services. 

In many current cable systems, including most urban systems, optical fiber networks have mostly replaced

the use of CARS microwave links. In some cable systems, especially rural cable systems, some additional

CARS channels were needed to fill the wider cable bandwidths. The net effect of these changes is that a

large number of CARS channels have been taken out of daily service, even though the CARS license

information in Figure 3.5 does not reflect those changes. Accurate information on the number of CARS

licenses actually in use is not available for this report.

Private cable relay service at 18 GHz provides a function identical to CARS, except that private cable

customers are in large hotels or apartment complexes. Private cable microwave signals are sent directly to

each individual building where the operator intends to provide services (i.e., each building acts as a headend

site). The signals are distributed throughout the building or campus via coaxial cables, but the cables are

not allowed to cross a public right-of-way. By remaining “private” the private cable operator escapes many

regulatory obligations, including “must-carry” rules, local franchise agreements, and many more.

Moreover, the private cable operator is able to serve very large customers, while avoiding the expense of

building and maintaining an elaborate city-wide cable network. As with CARS, private cable microwave

requires a license for each channel at each destination. However, private cable must treat each building as

a separate destination. Thus, a single private cable hub might have as many as 2000 licences (72 channels

to each of 30 buildings). These factors have driven (and will continue to drive) the very rapid growth of

private cable microwave systems. 

As a result of serving only individual buildings, as well as being forbidden to cross public right-of-ways,

private cable has not developed any associated wide-area fiber optic networks. Therefore, at a time when

CATV is abandoning its CARS system in favor of large multipurpose optical fiber networks, private cable

at 18 GHz is still rapidly expanding its microwave distribution network. The lack of a fiber network to

support wideband two-way digital services in future private cable systems may present future growth

problems, especially since the large building complexes served by private cable are also especially targeted

by other competitive access providers (CAPs). In the future, in buildings served with fiber, private cable

services might be provided more economically via fiber. In buildings not served with fiber, microwave

delivery of private cable services might be economical, but delivery of 2-way digital services will be

strongly contested by other wireless access providers. Future development also depends crucially on future

regulatory decisions, including the degree to which private cable signals can cross public right-of-ways in

fiber belonging to someone else, the amount of common carrier-like traffic that can be carried on “private”
88

 Figure 3.6. Summary of fixed service licenses,

 not counting CARS/private cable.

systems, the possible imposition of more regulations, and the availability of other frequency bands to

replace 18 GHz spectrum lost to satellite systems.

In summary, earlier predictions of CARS license decreases in the 13 GHz band were in error partly because

cable operators have not yet returned unused CARS licenses and partly because of the need to distribute

additional video programming to fill wider-bandwidth cable systems. The rapid growth in the 18 GHz band

was mainly caused by the growth of a new service (private cable relay) and (to a lesser degree) by the need

to fill the new wider-bandwidth cable systems. At the time of the earlier staff study, 18 GHz private cable

was just starting up, and its future growth was completely overlooked by that study.

3.6 Summary

The license counts in private, broadcast auxiliary, and Federal Government services changed about as

predicted. Figure 3.6 summarizes growth in the major microwave service categories, not counting CARS

and Private Cable transport. Data on Federal fixed-only assignments were not available for the years before

1991. Noteworthy departures from predictions came from the 18-GHz private cable service, and the 2-GHz,

6-GHz, and 11-GHz common

carrier bands. In all cases, these

microwave bands grew more

rapidly than anticipated or did

not shrink as predicted. The

total number of licenses

associated with these services

reached a high point in 1994 and

has been approximately constant

since then.

The growth of CARS and

private cable in the 13 GHz and

18 GHz bands (shown in figure

3.5) is not included in figure

3.6. These services have grown

very rapidly, reaching 207,000

licenses in 1998, with growth

apparently continuing at a rate in

excess of 10% annually. Although the number of licenses in

CARS and private cable exceeds

the total number of licenses in

all of the other fixed services,

the large number of CARS

licenses at 13 GHz is quite misleading, since many of these licenses are no longer in use. Nevertheless, the

private cable service at 18 GHz continues to grow very rapidly, unlike most of the rest of the fixed services.

None of these microwave license counts include the use of unlicensed terrestrial links implemented in the

ISM bands using spread-spectrum technology and Part 15 rules. It is believed that 20,000 unlicensed

microwave point-to-point links have been installed for private and common carrier operations, mainly in

the 2.4 GHz and 5.8 GHz ISM bands. We note that one manufacturer suggests initially installing an

unlicensed link at 5.8 GHz and deciding later whether to change it to licensed operation in the 6 GHz or

6.5 GHz bands. 
89

Likewise, we are unable to collect current data in any of the rapidly-growing bands where area-wide

geographical licenses are granted, such as the 24 GHz and 39 GHz bands. For example, Winstar claimed

to have installed almost 200,000 lines by June 1998. Assuming that a third of these were installed with T1

microwave links (28 lines per link), these lines would represent about 2100 new links (equivalent to 4200

licenses) in the 39 GHz band alone.

The significance of the preceding two paragraphs is that some major growth trends may be invisible to our

data-gathering processes. If the stated assumptions are correct (not necessarily so), the number of

microwave links has been continuing to grow, instead of leveling off as indicated by license counts.

However, we also believe that some microwave license counts are inflated by unused links (especially at

4 GHz and 13 GHz) and churn in the cellular/PCS bands, and we believe that the newer microwave links

tend to be lower-capacity and shorter-range links than were traditionally built (especially in the common

carrier service). Therefore, the present population count of licensed microwave links may represent less

spectrum use and less investment than earlier populations, but it may also miss an increasing number of

links that are not individually licensed.

4. PREDICTIONS FOR FUTURE USAGE

Predictions of usage on a band-by-band basis are particularly problematic now. The rechannelization and

private and public sharing of most of the bands has introduced new factors that destroy some of the

relevance of band-by-band historical data. The further blurring of distinctions between private and public

carriers, between cable TV operators and LECs, between CARS and private cable relay systems, and even

between fixed and mobile services under the "wireless" label may cause difficulties in identifying the

general industrial categories into which future predicted operations should be placed. Finally, the expanded

use of equipment that is not individually licensed (because of geographical area licensing or the use of nonlicensed bands) may make license databases less useful as a source of information. Nevertheless, the

following general predictions can be made.

4.1 Federal Government

Federal Government use of fixed services will remain approximately constant. Factors decreasing the

number of Federal assignments include a general downsizing of many Federal Government facilities

(especially military facilities) and the continually improving capability of commercial communications to

meet present and future Federal needs. These will cause a slow continued shift of non-military

telecommunication services from agency-owned networks to commercial services. On the other hand,

Federal use of communications and the associated information technologies will continue to grow

substantially, in many diverse activities. In particular, military use of communications and information

technologies as a “force multiplier” will tend to increase military communication requirements generally,

including military use of fixed services. Moreover, military communications tend to have requirements

which are quite different from those of many commercial users (and, thus, not easily converted to

commercial services). Overall, it is expected that Federal fixed service assignments will remain constant

over the next 5 years.

4.2 Private Operational Use

Private microwave licenses will decrease in the frequency bands below 6 GHz and increase in the bands

above 6 GHz. The decrease in the lower frequency bands will be driven by the need to vacate the 2 GHz
90

PCS bands, including the bands in the 2110-2200 MHz range. Some of the growth in the higher frequency

bands will be migration from the 2 GHz bands, but much will be a continuing slow expansion of the

traditional private microwave services to industry and government. The private microwave service is

expected to show no net annual growth over the next five years. Private cable systems are not included in

this estimate.

Since BSS services have finally been established in the 12.2-12.7 GHz band, there may be an accelerated

departure of old microwave users from that band. Since the 4 GHz, 6 GHz, and 11 GHz common carrier

bands, with bandwidths up to 40 MHz, are now available for private use, there may be new opportunities

for private companies to establish wideband internal microwave services.

The rapid recent growth of microwave services intended to support private cable TV systems will continue

for a few years. After a few years, however, it will face considerable competition from other forms of

video distribution, especially two-way urban fiber networks designed to provide two-way broadband

services. 

Private microwave services used to bypass LEC’s over relatively long distances may be somewhat

diminished by very competitive services provided by fiber-based or microwave-based competitive access

providers acting as common carriers. Narrowband and remote SCADA applications will meet increased

competition from new low-cost satellite and PCS wireless-data applications.

It is predicted that there will be very substantial growth of fixed microwave systems in WLANs and similar

home-based or business-based private communication systems in the future, but much of this growth will

not be licensed and cannot be included in estimates based on the number of licensed systems. Instead, this

growth will be accomplished under Part 15, ISM, unlicensed PCS, or U-NII rules.

4.3 Common Carrier Services

Common carrier microwave licenses will continue net growth, but this net growth will be the result of

several divergent trends. Common carrier traffic will continue to expand rapidly. However, a continually

larger proportion of common carrier communications will be carried on optical fiber. Microwave links will

continue to be valuable for rapidly growing systems and are expected to continue to have extensive

application in cellular and PCS industries. New fixed microwave applications, including WLL, ILEC

bypass, and other high-density fixed services (HDFS) may greatly expand the use of higher-frequency

microwave bands for short range links to access individual customers. Some of these trends might be

difficult to track, especially since many of these short-range links will not be individually licensed.

The number of licenses in the 2 GHz band will begin to drop rapidly when future details on the use of the

remainder of those frequencies are determined and the bands must be vacated to make room for new PCS

and satellite services. Until then, however, there will be continued 2-GHz support of cellular/PCS systems.

The role of the 2.3 GHz WCS bands is currently unknown; possibly they will become a migration

destination for displaced 2-GHz fixed systems, upstream links for two-way digital MMDS, or audio

satellite broadcasting. The migration out of the 4 GHz band will continue. Although the future role of

backyard TVRO systems as a "spoiler" for the 4 GHz band seems likely to diminish somewhat (because

competition from 12-GHz BSS systems is reducing the number of 4-GHz TVROs), severe problems with

licensed satellite downlinks will continue.

Cellular and PCS operations will move strongly into the bands above 10 GHz, with growth expected

specifically in the 10.5 GHz, 11 GHz, 18 GHz and 39 GHz bands. Much growth is expected in bands that

were previously limited to private services, particularly since these bands have the majority of the
91

narrower channelization plans. The original common carrier bands, especially 6 and 11 GHz, will tend to

be used especially for longer range, wideband, high-traffic requirements. Though it is evident that there

will be major activity in all common carrier bands, it is not yet clear how the future cellular and PCS

backbone infrastructure will be shared between microwave, copper, and fiber technologies.

Rates at which some of the new HDFS technologies will be developed remain subject to uncertainty, but

these new technologies will probably drive huge growth in microwave markets. Broadband WLL (24 GHz)

and wireless fiber (38 GHz) are common carrier technologies that could be very successful. In addition,

LMDS and MMDS may grow rapidly in the near future and may carry substantial amounts of two-way

traffic (telephone and Internet services) to its subscribers. The reader should recognize that these new

technologies represent a fundamental shift in the use of microwaves by common carriers to provide

“access” to customers, instead of using microwaves mainly for internal signal transport. It is expected that

the growth of licenses in some of these new services may not be useful in tracking the number of

transmitters, since the transmitters will usually not be individually licensed. 

Not counting licenses used for individual consumer access in the new systems (a reasonable assumption,

since most of these applications will not be individually licensed), it is expected that traditional common

carrier licenses will increase by 1% annually. However, there will be much growth in common carrier

services that are not individually licensed.

It is not completely clear what criteria should be used to track future common carrier microwave growth,

even if the data were available. Although it would be very useful to have data available on the number of

nonlicensed transmitters, other problems would still remain. For example, many of the new systems that

will be used in the 24 GHz, 28 GHz, and 39 GHz bands may use adaptive point-to-multipoint architectures.

These systems might continually adjust the bandwidth and direction of radio “beams” from a hub site,

depending on the instantaneous traffic requirements of individual users. How should the capacity of such

hubs be compared in a meaningful way to a traditional point-to-point link? Does a short-range indoor WLL

link (e.g., a cordless phone supplied by the LEC) count the same as a 30-km DS-3 path? The question is

not merely academic, since answers are needed before one can choose useful growth criteria that can form

the basis for a prediction of growth. This problem is particularly vexing in the rapidly-changing common

carrier environment.

4.4 Broadcast Auxiliary Services

Broadcast auxiliary licenses will increase, based on the need to provide more local video coverage and to

support a variety of HDTV, SDTV, and conventional TV programming. This does not necessarily mean

that additional spectrum will be needed, however, since digital compression techniques will allow the

existing ENG wideband analog FM channels (currently 15-25 MHz bandwidth) to be narrowed, doubling

or tripling the number of channels from the current spectrum. There will be a massive adjustment in STL

systems when broadcasters convert their systems to the new digital technologies and begin to support

multiple channels and non-video formats. Existing analog FM STLs can be replaced with single digital STLs

carrying digitized NTSC and HDTV signals. Some broadcasters will use this transition as an opportunity

to switch microwave STLs to fiber, possibly in cooperation with other broadcasters using shared broadcasting/tower facilities. Over the long run, continually more fixed functions like STLs will be carried on

fiber. It is predicted that total broadcast auxiliary licenses will increase 5% annually over the next 5 years.
92

4.5 CARS and Private Cable

CARS licenses will decrease substantially over the next 5 years, following the conversion of many cable

systems to digital fiber systems utilizing two-way architectures. This decrease was predicted to have begun

already, but cable operators have been slower than expected in converting to two-way digital systems.

Moreover, following system conversion, operators have not been quick to turn in unused licenses, so that

the 123,000 CARS licenses shown in Figure 2.27-3 overstate the number of licenses in actual daily use. 

At this time, large MSOs are aggressively building two-way networks and are beginning to deploy some

advanced cable services, such as high-speed cable modems for Internet access. The proposed TCI/AT&T

merger is based on a widespread and rapid implementation of a 2-way digital cable network providing a full

range of advanced cable services. Urban cable systems should be mostly converted to two-way architectures

before the end of 1999, with rural systems lagging by several years. It is difficult to understand what

functions (if any) CARS will provide in the new two-way digital cable systems. Nevertheless, the existing

CARS systems still represent a wireless plant of extremely wide bandwidth communications capacity, albeit

one-way only, located in the heart of many urban areas. That might be something useful. 

Private cable microwave will continue to grow for a few years at a 10% annual growth, depending partly

on continued favorable regulatory decisions. The prospect of long term continued growth is less certain.

More than half of the 18-GHz private cable spectrum has been proposed for reallocation to satellite services

on a primary basis, jeopardizing the spectrum used for future private cable systems. In addition, the

multiple dwelling unit (MDU) customers served by private cable will also be early targets for many other

fiercely competitive new technologies, including fiber, CATV, BSS, MMDS, LMDS, 24 GHz, and 39

GHz. 

4.6 HDFS and Non-traditional Fixed Services

A number of new fixed services will assume prominence in the next 5 years, including some of the proposed

high density fixed services (HDFS). Although these services nominally might be included in the common

carriers designation (Section 4.4), we have included these services in a separate new category. Wireless

local loop services will begin to be provided in the 24 GHz band, as well as other DEMS services such as

WLANs. These services may grow very rapidly, made possible by new technologies for manufacturing

higher frequency semiconductor devices. However, depending how these services are licensed (e.g. by

geographical area), it may be useless to try to track their growth by merely counting the number of areawide licenses auctioned.

The 39 GHz band is growing rapidly, mainly based on Winstar’s deployment of their “wireless fiber”

network. This growth will be accelerated following auctions that will distribute many additional BTA-wide

licenses to other users, especially if the Winstar business plan is successful. 

LMDS will be widely deployed in the 28/31 GHz band, beginning in urban areas. This service will provide

broadband data and (only in some cases) video entertainment. Similar services will be provided in rural

areas using a two-way digital version of MMDS. Unlicensed point-to-point and WLAN services will

continue to grow rapidly in the 2.4 GHz and 5.8 GHz ISM bands, the 5 GHz U-NII band, and possibly in

the newly allocated 59-64 GHz unlicensed band. Short-range in-home or in-office wireless computer

interconnection and home appliance interconnection may become popular—presumably in the ISM bands

or in the unlicensed PCS and U-NII bands.
93

It is difficult to know whether all (or any) of these applications will be commercially successful (and, if they

are successful, whether to count them as part of the traditional fixed services in the next fixed services

report). Not only are these totally new applications, but they are still changing. MMDS and LMDS, for

example, started out as alternative ways to distribute analog TV. They are now becoming super-CLECs,

offering telephone, high-speed Internet access, and video entertainment. Who knows what they will be ten

years from now? Industry is making its predictions backed with billions of dollars of capital investment. The

author hesitates even to venture a guess, but it will be very interesting to see how things work out.

4.8 Summary of Predictions

The future use of traditional microwave systems will be squeezed into niche markets representing a

continuously smaller percentage of a continuously larger total telecommunications market. At present, these

opposing trends have approximately balanced out, resulting in fairly stable net use of licensed microwave

communications. Similar results are expected for the next five years, with predictions for the more distant

future becoming more uncertain (with approximately equal portions of optimism or pessimism).

Although the traditional niche markets are expected to show little net growth, they will continue to provide

very important services that have few obvious alternatives. The long-range low-density applications, suitable

for SCADA or to bring communications to smaller remote communities, will remain crucial to areas not

served by other suitable media. Microwave will continue to have deployment advantages in areas where

terrain (including the very complex and expensive urban terrain) causes problems for installation of copper

and fiber cables. The ability to use microwave systems to bring instant connectivity to rapidly changing

cellular/PCS systems (as well as other short-term scheduled and emergency uses) will remain a major

microwave advantage over competing technologies. Finally, microwaves will continue to be used for highreliability, earthquake- and backhoe-proof critical circuits. However, the continued massive installation of

additional fiber by LECs, CLECs and CAPs, the deployment of wideband two-way digital cable systems,

the new availability of narrowband and wideband satellite systems, and the continued development of

wireline pair-gain technologies (e.g., xDSL) will continue to erode the geographical areas and the specific

applications where microwave technology is the only obvious choice. 

Although the continuing requirements for the traditional microwave transport applications will probably not

increase significantly, there may be rapid growth of several new microwave applications. These fastgrowing applications include many HDFS and short-range access applications, operating in the higher

frequency bands where smaller antennas and wider bandwidths are fortuitously available. These

applications will tend to serve individual users and small groups of users—often with nonlicensed, massmarketed equipment. These applications are associated with acronyms like WLL, MMDS, LMDS, FWA,

U-NII, WLAN, and more. It is too early to predict which of these systems will become significant

components of a future microwave industry, though many of these applications are being aggressively

developed at the present time. Some of these new applications may form the basis for future ubiquitous

microwave systems, deployed on a scale that is barely imaginable today. 
94

[1] Fiber deployment update, End of year 1997. Jonathan M. Kraushaar, Industrial Analysis Division,

 Common Carrier Bureau, Federal Communications Commission. 

[2] C. T. Troy, “Fiber, fiber, who’s got the fiber?” Photonics Spectra, p. 52, Dec. 1996

[3] FCC 93-350. Second report and order. Adopted July 15, 1993, released August 13, 1993.

[4] Hurt, Cerezo, Drocella, Kitzmiller, and Wilson. “Spectrum Reallocation Final Report. Response 

 to Title VI - Omnibus Budget Reconcilliation Act of 1993.” NTIA Special Publication 95-32 

 Feb. 1995.

[5] E. F. Drocella, S. K. Jones, and W. T. Druhan. “Spectrum Reallocation Report. Response to 

 Title III of the Balanced Budget Act of 1997.” NTIA Special Publication 98-36. Feb. 1998.

[6] FCC 95-47. Allocation of spectrum below 5 GHz transferred from Federal Government Use. First

 Report and Order and Second Notice of Proposed Rulemaking. Adopted February 7, 1995.

[7] FCC 98-309 Memorandum Opinion and Order and Third Notice of Proposed Rulemaking and 

 Order, November 19, 1998.

[8] K.Nebbia, Long, and Sussman, "Spectrum Resource Assessment of the Federal Government -

 Fixed Service (Bands above 400 MHz)." NTIA TM-127. Sep. 1987.

[9] P. Marrangoni, et al. “Creating new technology bands for emerging telecommunications

 technology.” FCC, Office of Engineering and Technology, OETS/TS 92-1. Table 1. p.8.

[10] FCC Report and Order. Amendment of Parts 21 and 74 to enable MDS and ITFS licensees to

 engage in fixed two-way transmissions. Dockets MM 97-217 and RM-9060. Adopted 09/17/98.

[11] FCC “Annual assessment of the status of competition in the markets for the delivery of video 

 programming,” Fifth annual report, released 12/23/98. CS Docket 98-102. See paragraph 80.

[12] FCC Order In the matter of Transmissions Holding, Inc., released March 10, 1999.

[13] FCC 98-235. NPRM adopted September 17, 1998, released September 18, 1998.

[14] FCC 98-336. Report and Order adopted December 17, 1998, released December 23, 1998.

[15] FCC - ET Docket No. 94-124, RM-8308, RM-8784, and WT Docket 98-136. Memorandum

 Opinion and Order on Reconsideration and NPRM. Adopted July 29, 1998. Amendment of

 Parts 2, 15, and 97 of the Commission’s Rules to permit use of radio frequencies above 40 GHz

 for new radio applications, etc.

[16] FCC ET Docket No. 94-124 and RM-8308. Amendment of Parts 2 and 15 of the Commissions's

 Rules to per use of radio frequencies above 40 GHz for new radio applications. NPRM released

 November 8 1994.

[17] F. Sanders and V. Lawrence, “Broadband spectrum survey at Denver, Colorado,” NTIA Report

 95-321, Sep. 1995. 

5. REFERENCES
95

[18] F. Sanders, B. Ramsey, and V. Lawrence, “Broadband spectrum survey at San Diego,

 California,” NTIA Report 97-334. Dec. 1996.

[19] F. Sanders, B. Ramsey, and V. Lawrence, “Broadband spectrum survey at Los Angeles,

 California,” NTIA Report 97-336. May 1997