**NTIA Report 06-440**

**FEDERAL LAND MOBILE OPERATIONS**

**IN THE 162-174 MHz BAND**

**IN THE WASHINGTON, D.C. AREA**

***Phase 1: STUDY OF AGENCY OPERATIONS***

**Report Series**

**August 2006**

![](media/image1.jpeg){width="1.7604166666666667in" height="1.75in"}

**U.S. Department of Commerce**

National Telecommunications and Information Administration

**Page/Blank**

**NTIA Report 06-440**

**FEDERAL LAND MOBILE OPERATIONS**

**IN THE 162-174 MHz BAND**

**IN THE WASHINGTON, D.C. AREA**

***Phase 1: STUDY OF AGENCY OPERATIONS***

**Report Series**

**August 2006**

![](media/image1.jpeg){width="1.3763888888888889in"
height="1.3645833333333333in"}

**U.S. DEPARTMENT OF COMMERCE**

**Carlos M. Guiterrez, Secretary**

John M.R. Kneuer

Acting Assistant Secretary

For Communications and Information

**Page/Blank**

**PROJECT MANAGEMENT**

Fredrick R. Wentland

*Associate Administrator*

*Office of Spectrum Management*

Edward F. Drocella

*Chief, Spectrum Engineering and Analysis Division*

**TEAM LEADER**

Gary Patrick

**REPORT AUTHORS**

Charles Hoffman

Robert Matheson

Fred Najmy

Robert Wilson

Page/Blank

**ACKNOWLEDGEMENTS**

The authors would like to thank the following National
Telecommunications and Information Administration (NTIA) personnel for
their review and contributions to this report: Gerald Hurt, Spectrum
Engineering and Analysis Division (SEAD); Thomas Sullivan, SEAD; Edward
Drocella, SEAD; Cecilia Tucker, SEAD; Marianne Wiler, Information
Technology Division; Margaret Luebs, Institute for Telecommunications
Sciences, Boulder, Colorado; and Suzette Williams, Spectrum Services
Division.

The authors are especially grateful to the representatives from the
various federal agencies that took the time to provided valuable
information on their current operations and future plans.

Page/Blank

TABLE OF CONTENTS

[LIST OF TABLES iii](#__RefHeading___Toc71359925)

[LIST OF FIGURES iv](#__RefHeading___Toc71359926)

[GLOSSARY vii](#__RefHeading___Toc71359927)

[EXECUTIVE SUMMARY ix](#__RefHeading___Toc71359928)

[SECTION 1 INTRODUCTION 1-1](#introduction)

[1.1 Background 1-1](#background)

[1.2 Scope of Work 1-5](#scope-of-work)

[1.2.1 Overall Objective 1-5](#overall-objective)

[1.2.2 Specific Objectives 1-5](#specific-objectives)

[1.2.3 Other Related Work 1-6](#other-related-work)

[SECTION 2 PHASE 1 OVERVIEW 2-1](#phase-1-overview)

[2.1 General 2-1](#general)

[2.2 Concept of the Signal Capacity Analysis Program (SCAP)
2-2](#concept-of-the-signal-capacity-analysis-program-scap)

[2.3 Selection of 162-174 MHz Band in the Washington, D.C. area
2-3](#selection-of-162-174-mhz-band-in-the-washington-d.c.-area)

[2.4 Sources of Current Usage Data 2-3](#sources-of-current-usage-data)

[SECTION 3 CHARACTERISTICS OF MOBILE RADIO SYSTEMS
3-1](#characteristics-of-mobile-radio-systems)

[3.1 General 3-1](#general-1)

[3.1.1 Simplex radio systems 3-1](#simplex-radio-systems)

[3.1.2 Radio Repeater Systems 3-2](#radio-repeater-systems)

[3.1.3 Mobile Talk-Around Mode 3-3](#mobile-talk-around-mode)

[3.1.4 Multi-Site Repeater Systems 3-3](#multi-site-repeater-systems)

[3.1.5 Half-Duplex Radio Systems 3-4](#half-duplex-radio-systems)

[3.1.6 Multi-Site Duplex Systems 3-5](#multi-site-duplex-systems)

[3.1.7 Receive-Only Sites 3-6](#receive-only-sites)

[3.1.8 Simulcast Radio Systems 3-7](#simulcast-radio-systems)

[3.1.9 Trunked Radio Systems 3-8](#trunked-radio-systems)

[3.2 Summary 3-9](#summary)

[SECTION 4 FEDERAL OPERATIONS IN THE 162-174 MHz BAND
4-1](#federal-operations-in-the-162-174-mhz-band)

[4.1 General 4-1](#general-2)

[4.2 Allocation 4-1](#allocation)

[4.2.1 Use of the 162-174 MHz Band 4-3](#use-of-the-162-174-mhz-band)

[4.3 Operational Description of Each Agency's LMR Operations
4-10](#operational-description-of-each-agencys-lmr-operations)

[4.3.1 United States Department of Agriculture (USDA)
4-10](#united-states-department-of-agriculture-usda)

[4.3.2 United States Department of Commerce (DOC)
4-11](#united-states-department-of-commerce-doc)

[4.3.3 United States Coast Guard (USCG)
4-13](#united-states-coast-guard-uscg)

[4.3.4 United States Department of Defense (DOD)
4-14](#united-states-department-of-defense-dod)

[4.3.5 United States Department of Energy (DOE)
4-15](#united-states-department-of-energy-doe)

[4.3.6 Federal Aviation Administration (FAA)
4-16](#federal-aviation-administration-faa)

[4.3.7 United States Department of Homeland Security (DHS)
4-17](#united-states-department-of-homeland-security-dhs)

[4.3.8 United States Department of Interior (DOI)
4-18](#united-states-department-of-the-interior-doi)

[4.3.9 United States Department of Justice (DOJ)
4-19](#united-states-department-of-justice-doj)

[4.3.10 United States Department of the Treasury (Treasury)
4-20](#united-states-department-of-the-treasury-treasury)

[4.3.11 United States Capital Police (USCP)
4-21](#united-states-capital-police-uscp)

[4.3.12 United States Postal Service (USPS)
4-23](#united-states-postal-service-usps)

[4.3.13 United States Department of Veteran's Affairs (VA)
4-24](#united-states-department-of-veterans-affairs-va)

[4.3.14 Other Agencies or Bureaus 4-25](#other-agencies-or-bureaus)

[4.4 Summary 4-26](#summary-1)

[SECTION 5 OTHER FEDERAL GOVERNMENT EFFORTS
5-1](#other-federal-government-efforts)

[5.1 General 5-1](#general-3)

[5.2 Migration to Narrowband Technology
5-1](#migration-to-narrowband-technology)

[5.3 Technical Performance Standards
5-2](#technical-performance-standards)

[5.3.1 Trunking Technology 5-3](#trunking-technology)

[5.3.2 162-174 MHz Band Restructuring 5-3](#mhz-band-restructuring)

[5.3.3 Frequency Reuse 5-3](#frequency-reuse)

[5.4 Initiatives And Spectrum Efficiency Improving Programs
5-4](#initiatives-and-spectrum-efficiency-improving-programs)

[5.4.1 NTIA Spectrum Summit 5-4](#ntia-spectrum-summit)

[5.4.2 Federal Communication Commission's Spectrum Policy Task Force
5-5](#federal-communication-commissions-fcc-spectrum-policy-task-force)

[5.4.3 Government Accounting Office Reports
5-5](#general-accounting-office-gao-reports)

[5.4.4 Presidential Initiative to Develop, Implement Spectrum Policy for
the 21st Century
5-6](#presidential-initiative-to-develop-implement-spectrum-policy-for-the-twenty-first-century)

[5.4.5 SAFECOM Program Office 5-7](#safecom-program-office)

[5.4.6 1COMMWIRELESS (Formerly FEDSMR)
5-7](#commwireless-formerly-fedsmr)

[5.4.7 Integrated Wireless Network (IWN)
5-8](#integrated-wireless-network-iwn)

[5.4.8 United States Department of Defense Trunked Network
5-9](#united-states-department-of-defense-trunked-network)

[SECTION 6 THE SIGNAL CAPACITY ANALYSIS PROGRAM (SCAP)
6-1](#the-signal-capacity-analysis-program-scap)

[6.1 General 6-1](#general-4)

[6.2 Definition of Signal Capacity 6-1](#definition-of-signal-capacity)

[6.3 Basic SCAP Analysis 6-3](#basic-scap-analysis)

[6.3.1 Peak and Average Signal Capacity Maps
6-4](#peak-and-average-signal-capacity-maps)

[6.3.2 The Use of Function Codes to define Signal Capacity of Networks
6-7](#the-use-of-function-codes-to-define-signal-capacity-of-networks)

[SECTION 7 FEDERAL AGENCY SIGNAL CAPACITY MAPS
7-1](#federal-agency-signal-capacity-maps)

[7.1 General 7-1](#general-5)

[7.2 Technical parameters for Signal Capacity Maps
7-1](#technical-parameters-for-signal-capacity-maps)

[7.3 Interpreting the Signal Capacity Maps
7-2](#interpreting-the-signal-capacity-maps)

[7.4 Signal Capacity Maps for Federal Agencies
7-7](#signal-capacity-maps-for-federal-agencies)

[7.4.1 United States Department of Agriculture (USDA)
7-10](#united-states-department-of-agriculture-usda-1)

[7.4.2 United States Coast Guard (USCG)
7-12](#united-states-coast-guard-uscg-1)

[7.4.3 United States Department of Commerce (DOC)
7-14](#united-states-department-of-commerce-doc-1)

[7.4.4 United States Department of Defense (DOD)
7-16](#united-states-department-of-defense-dod-1)

[7.4.5 United States Department of Energy (DOE)
7-18](#united-states-department-of-energy-doe-1)

[7.4.6 Federal Aviation Administration (FAA)
7-20](#federal-aviation-administration-faa-1)

[7.4.7 United States Department of Interior (DOI)
7-22](#united-states-department-of-interior-doi)

[7.4.8 United States Department of Justice (DOJ)
7-24](#united-states-department-of-justice-doj-1)

[7.4.9 United States Capitol Police (USCP)
7-26](#united-states-capitol-police-uscp)

[7.4.10 United States Postal Service (USPS)
7-28](#united-states-postal-service-usps-1)

[7.4.11 United States Department of Treasury (Treasury)
7-30](#united-states-department-of-treasury-treasury)

[7.4.12 United States Department of Veteran's Affairs (VA)
7-32](#united-states-department-of-veterans-affairs-va-1)

[7.4.13 Other Agencies 7-34](#other-agencies)

[7.4.14 All Federal Agencies 7-36](#all-federal-agencies)

[7.4.15 Integrated Wireless Network (IWN) (Departments of Justice,
Treasury and Homeland Security)
7-38](#integrated-wireless-network-iwn-united-states-departments-of-justice-treasury-and-homeland-security)

[7.4.16 All Federal Agencies minus IWN
7-40](#all-federal-agencies-minus-iwn)

[SECTION 8 SUMMARY OF FINDINGS 8-1](#summary-of-findings)

[APPENDIX A DESCRIPTION OF SIGNAL CAPACITY ANALYSIS PROGRAM
A-1](#description-of-signal-capacity-analysis-program)

[]{#__RefHeading___Toc71359925 .anchor}LIST OF TABLES

[Table 4‑1. International and National Frequency Allocations and
Footnotes for the 162-174 MHz Band 4-2](#__RefHeading___Toc71359286)

[Table 4‑2. Number of Frequency Assignments
4-3](#__RefHeading___Toc71359287)

[Table 4‑3. Number of Frequency Assignments within a 100 Mile Radius of
Washington, D.C. (162-174 MHz) 4-5](#__RefHeading___Toc71359288)

[Table 4‑4. Nationwide (US&P, USA, and US) and Statewide Assignments by
Agency 4-9](#__RefHeading___Toc71359289)

[Table 7‑1. Total Number of Assignments with Function Codes Included in
SCAP 7-7](#__RefHeading___Toc71359290)

[Table 7‑2. Total Number of Assignments with Function Codes Not Included
in SCAP Analysis 7-8](#__RefHeading___Toc71359291)

[Table 7‑3. U.S. Department of Agriculture Assignments and Function
Codes 7-11](#__RefHeading___Toc71359292)

[Table 7‑4. U.S. Coast Guard Assignment and Function Codes
7-13](#__RefHeading___Toc71359293)

[Table 7‑5. U.S. Department of Commerce Assignments and Function Codes
7-15](#__RefHeading___Toc71359294)

[Table 7‑6. U.S. Department of Defense Assignments and Function Codes
7-17](#__RefHeading___Toc71359295)

[Table 7‑7. U.S. Department of Energy Assignments and Function Codes
7-19](#__RefHeading___Toc71359296)

[Table 7‑8. Federal Aviation Administration Assignment and Function
Codes 7-21](#__RefHeading___Toc71359297)

[Table 7‑9. U.S. Department of Interior Number Assignments and Function
Codes 7-23](#__RefHeading___Toc71359298)

[Table 7‑10. U.S. Department of Justice Number Assignments and Function
Codes 7-25](#__RefHeading___Toc71359299)

[Table 7‑11. U.S. Capitol Police Assignment and Function Codes
7-27](#__RefHeading___Toc71359300)

[Table 7‑12. U.S. Postal Service Assignments and Function Codes
7-29](#__RefHeading___Toc71359301)

[Table 7‑13. U.S. Department of Treasury Assignments and Function Codes
7-31](#__RefHeading___Toc71359302)

[Table 7‑14. U.S. Department of Veteran's Affairs Assignments and
Function Codes 7-33](#__RefHeading___Toc71359303)

[Table 7‑15. "Other Agencies" Assignments and Function Codes
7-35](#__RefHeading___Toc71359304)

[Table 7‑16. All Federal Agencies Assignments and Function Codes
7-37](#__RefHeading___Toc71359305)

[Table 7‑17. IWN Assignments and Function Codes
7-39](#__RefHeading___Toc71359306)

[Table 7‑18. Non-IWN Assignments and Function Codes
7-41](#__RefHeading___Toc71359307)

[Table 8‑1. Maximum Peak Signal Capacity and Included Transmitters
8-2](#__RefHeading___Toc71359308)

[]{#__RefHeading___Toc71359926 .anchor}LIST OF FIGURES

[Figure 3‑1. Simplex Radio System 3-1](#__RefHeading___Toc71359226)

[Figure 3‑2. Repeater Architecture 3-2](#__RefHeading___Toc71359227)

[Figure 3‑3. Multi-Site Repeaters 3-4](#__RefHeading___Toc71359228)

[Figure 3‑4. Half-Duplex Radio System 3-5](#__RefHeading___Toc71359229)

[Figure 3‑5. Base Station Reception Augmented with Receive only sites
3-6](#__RefHeading___Toc71359230)

[Figure 3‑6. Simulcast System 3-7](#__RefHeading___Toc71359231)

[Figure 4‑1. Plot of all Agency Frequency Assignments within a 100 Mile
Radius of Washington, D.C. in the 162-174 MHz band
4-4](#__RefHeading___Toc71359232)

[Figure 4‑2. Plot of USDA Frequency Assignments within a 100 Mile Radius
of Washington, D.C. in the 162-174 MHz band.
4-11](#__RefHeading___Toc71359233)

[Figure 4‑3. Plot of DOC Frequency Assignments within a 100 Mile Radius
of Washington, D.C. in the 162-174 MHz band.
4-13](#__RefHeading___Toc71359234)

[Figure 4‑4. Plot of USCG Frequency Assignments within a 100 Mile Radius
of Washington, D.C. in the 162-174 MHz band.
4-14](#__RefHeading___Toc71359235)

[Figure 4‑5. Plot of DOD Frequency Assignments within a 100 Mile Radius
of Washington, D.C. in the 162-174 MHz band.
4-15](#__RefHeading___Toc71359236)

[Figure 4‑6. Plot of DOE Frequency Assignments within a 100 Mile Radius
of Washington, D.C. in the 162-174 MHz Band
4-16](#__RefHeading___Toc71359237)

[Figure 4‑7. Plot of FAA Frequency Assignments within a 100 Mile Radius
of Washington, D.C. in the 162-174 MHz Band.
4-17](#__RefHeading___Toc71359238)

[Figure 4‑8. Plot of DOI Frequency Assignments within a 100 Mile Radius
of Washington, D.C. in the 162-174 MHz
4-18](#__RefHeading___Toc71359239)

[Figure 4‑9. Plot of DOJ Frequency Assignments within a 100 Mile Radius
of Washington, D.C., in the 162-174 MHz band
4-20](#__RefHeading___Toc71359240)

[Figure 4‑10. Plot of Treasury Frequency Assignments within a 100 Mile
Radius of Washington, D.C., in the 162-174 MHz band
4-21](#__RefHeading___Toc71359241)

[Figure 4‑11. Plot of USCP Frequency Assignments within a 100 Mile
Radius of Washington, D.C., in the 162-174 MHz Band.
4-22](#__RefHeading___Toc71359242)

[Figure 4‑12. Plot of USPS Frequency Assignments within a 100 Mile
Radius of Washington, D.C., in the 162-174 MHz Band.
4-24](#__RefHeading___Toc71359243)

[Figure 4‑13. Plot of VA Frequency Assignments within a 100 Mile Radius
of Washington, D.C. in the 162-174 MHz Band.
4-25](#__RefHeading___Toc71359244)

[Figure 4‑14. Plot of Other Agency or Bureau Frequency Assignments
within a 100 Mile Radius of Washington, D.C. in the 162-174 MHz Band.
4-26](#__RefHeading___Toc71359245)

[Figure 6‑1. Peak Signal Capacity Coverage Map Examples
6-4](#__RefHeading___Toc71359246)

[Figure 6‑2. Average Signal Capacity Map Examples
6-5](#__RefHeading___Toc71359247)

[Figure 6‑3. PSC Map for Four Transmitters Analyzed as a Simulcast
System 6-8](#__RefHeading___Toc71359248)

[Figure 6‑4. PSC Map for Four Transmitters Analyzed as a Trunked System
6-8](#__RefHeading___Toc71359249)

[Figure 6‑5. ASC Map for Four Transmitters Analyzed as a Simulcast radio
System 6-9](#__RefHeading___Toc71359250)

[Figure 6‑6. ASC Map for Four Transmitters Analyzed as a Trunked Radio
System. 6-9](#__RefHeading___Toc71359251)

[Figure 7‑1. Peak Signal Capacity Map for Several Federal Radio Systems
7-2](#__RefHeading___Toc71359252)

[Figure 7‑2. Average Signal Capacity Map for Several Federal Radio
Systems 7-5](#__RefHeading___Toc71359253)

[Figure 7‑3. Peak Signal Capacity Map for U.S. Department of
Agriculture. 7-10](#__RefHeading___Toc71359254)

[Figure 7‑4. Average Signal Capacity Map for U.S. Department of
Agriculture 7-11](#__RefHeading___Toc71359255)

[Figure 7‑5. Peak Signal Capacity Map for U. S. Coast Guard
7-12](#__RefHeading___Toc71359256)

[Figure 7‑6. Average Signal Capacity Map for U. S. Coast Guard
7-13](#__RefHeading___Toc71359257)

[Figure 7‑7. Peak Signal Capacity Map for U.S. Department of Commerce
7-14](#__RefHeading___Toc71359258)

[Figure 7‑8. Average Signal Capacity Map for U.S. Department of Commerce
7-15](#__RefHeading___Toc71359259)

[Figure 7‑9. Peak Signal Capacity Map for U.S. Department of Defense
7-16](#__RefHeading___Toc71359260)

[Figure 7‑10. Average Signal Capacity Map for U.S. Department of Defense
7-17](#__RefHeading___Toc71359261)

[Figure 7‑11. Peak Signal Capacity Map for U.S. Department of Energy
7-18](#__RefHeading___Toc71359262)

[Figure 7‑12. Average Signal Capacity for U.S. Department of Energy
7-19](#__RefHeading___Toc71359263)

[Figure 7‑13. Peak Signal Capacity for the Federal Aviation
Administration 7-20](#__RefHeading___Toc71359264)

[Figure 7‑14. Average Signal Capacity for the Federal Aviation
Administration 7-21](#__RefHeading___Toc71359265)

[Figure 7‑15. Peak Signal Capacity for U.S. Department of Interior
7-22](#__RefHeading___Toc71359266)

[Figure 7‑16. Average Signal Capacity for U.S. Department of Interior
7-23](#__RefHeading___Toc71359267)

[Figure 7‑17. Peak Signal Capacity Map for U.S. Department of Justice
7-24](#__RefHeading___Toc71359268)

[Figure 7‑18. Average Signal Capacity Map for U.S. Department of Justice
7-25](#__RefHeading___Toc71359269)

[Figure 7‑19. Peak Signal Capacity Map for U. S. Capitol Police
7-26](#__RefHeading___Toc71359270)

[Figure 7‑20. Average Signal Capacity Map for U. S. Capitol Police
7-27](#__RefHeading___Toc71359271)

[Figure 7‑21. Peak Signal Capacity for U.S. Postal Service
7-28](#__RefHeading___Toc71359272)

[Figure 7‑22. Average Signal Capacity for U.S. Postal Service
7-29](#__RefHeading___Toc71359273)

[Figure 7‑23. Peak Signal Capacity for U.S. Department of Treasury
7-30](#__RefHeading___Toc71359274)

[Figure 7‑24. Average Signal Capacity Map for U.S. Department of
Treasury 7-31](#__RefHeading___Toc71359275)

[Figure 7‑25. Peak Signal Capacity Map for U.S. Department of Veteran's
Affairs 7-32](#__RefHeading___Toc71359276)

[Figure 7‑26. Average Signal Capacity Map for U.S. Department of
Veteran's Affairs 7-33](#__RefHeading___Toc71359277)

[Figure 7‑27. Peak Signal Capacity Map for "Other Agencies"
7-34](#__RefHeading___Toc71359278)

[Figure 7‑28. Average Signal Capacity Map for "Other Agencies"
7-35](#__RefHeading___Toc71359279)

[Figure 7‑29. Peak Signal Capacity map for all Federal Agencies
7-36](#__RefHeading___Toc71359280)

[Figure 7‑30. Average Signal Capacity map for all Federal Agencies
7-37](#__RefHeading___Toc71359281)

[Figure 7‑31. Peak Signal Capacity Map for IWN Agencies
7-38](#__RefHeading___Toc71359282)

[Figure 7‑32. Average Signal Capacity Map for IWN Agencies
7-39](#__RefHeading___Toc71359283)

[Figure 7‑33. Peak Signal Capacity for Non-IWN Agencies
7-40](#__RefHeading___Toc71359284)

[Figure 7‑34. Average Signal Capacity Map for Non-IWN Agencies
7-41](#__RefHeading___Toc71359285)

Page vi/Blank

[]{#__RefHeading___Toc71359927 .anchor}GLOSSARY

ANSI American National Standards Institute

apco Association of Public-Safety Communications Officials International

ASC Average Signal Capacity

ATF Bureau of Alcohol, Tobacco, and Firearms

blm Bureau of Land Management

BOP Bureau of Prisons

C3 Command, Control, and Communications

CTCSS continuous Tone Coded Squelch System

dea Drug Enforcement Administration

DES Data Encryption Standard

dhs United States Department of Homeland Security

DOC United States Department of Commerce

DOD United States Department of Defense

DOI United States Department of the Interior

DOJ United States Department of Justice

DOT United States Department of Transportation

EMC Electromagnetic Compatibility

faa Federal Aviation Administration

fbi Federal Bureau of Investigation

FCC Federal Communications Commission

FEDSMR Federal Specialized Mobile Radio System

FLETC Federal Law Enforcement Training Center

GAO United States General Accounting Office

GMF government Master File

GPS Global Positioning System

IP Internet Protocol

IRAC Interdepartment Radio Advisory committee

ITS Institute for Telecommunications Sciences

IWN Integrated Wireless Network

JSMS Joint Spectrum Management System

khz Kilohertz

LMR Land Mobile Radio

MHz Megahertz

NIST National Institute of Standards and Technology

NOAA National Oceanic and Atmospheric Administration

NOI Notice of Inquiry

NPRM Notice of Proposed Rulemaking

NRCS National Radio Communications System

NTIA national Telecommunications and Information Administration

NWR NOAA Weather Radio

NWS National Weather Service

OTAR Over-The-Air Re-keying

PCS Personal Communications Service

PSC Peak Signal Capacity

R-21 Rescue 21

RSMS radio Spectrum Measurement System

RO receive Only

sAFECOM Public Safety Communications Interoperability Program

SC Signal Capacity

SCAP Signal Capacity Analysis Program

S/I Signal-to-Interference Ratio

TIA Telecommunications Industry Association

Treasury United States Department of the Treasury

UHF Ultra High Frequency

USCG United States Coast Guard

USCP United States Capitol Police

USDA United States Department of Agriculture

USFS United States Forest Service

USPP united States Park Police

USPS United States Postal Service

USSS United States Secret Service

VA Department of Veteran's Affairs

VHF Very High Frequency

VoIP Voice over Internet Protocol

[]{#__RefHeading___Toc71359928 .anchor}EXECUTIVE SUMMARY

The National Telecommunications and Information Administration (NTIA),
an agency of the U.S. Department of Commerce, is responsible for
managing federal agency use of the radio spectrum. The NTIA establishes
policies concerning frequency assignment, allocation and use, and
provides the various federal departments and agencies with guidance to
ensure that their conduct of telecommunications activities is consistent
with these policies. The NTIA also serves under the Executive Branch as
the President\'s principal adviser on telecommunication policies
pertaining to the nation\'s economic and technological advancements and
to the regulation of the telecommunications industry.

Since the radio frequency spectrum is a finite natural resource, the
efficient use of this resource must be an important goal within the
government sector (federal, state and local) and the private/commercial
telecommunications sector. Historically, the efficient use of this
spectrum by the federal government has primarily been a process of
self-policing, peer review, and regulatory control. As demand for
spectrum has increased, NTIA and the Federal Communications Commission
(FCC) have continued to examine policies and regulations regarding the
efficient use of the spectrum to ensure that there will be adequate
spectrum for growth of existing services and available spectrum for new
services.

There are various methods to improve the spectrum efficiency of mobile
radio systems used by federal agencies. These methods include decreasing
bandwidth, increasing geographical frequency reuse, increasing the
number of users on a given frequency, and using trunked radio systems,
among others. The federal government has expended considerable effort in
the past to ensure that its use of the spectrum is as technically
efficient as practicable by adopting various spectrum efficient
technologies such as narrowbanding, sharing, overlaying, and applying
more realistic spectrum distribution, analytical, and planning
techniques. Although these methods are well-known in the federal land
mobile user community and NTIA has encouraged their adoption, agencies
have not applied them widely, since the methods also have substantial
disadvantages. In most cases, the disadvantage is a higher cost (e.g.,
the requirement to buy new equipment to replace older, less-efficient
systems), but sometimes it includes a decrease in functionality which
could negatively affect the agency's ability to perform its mission.

Therefore, an expanded "measure" for new mobile radio technologies has
been consolidated under the title of "effectiveness." Effectiveness
includes spectrum efficiency, usability and cost factors. Usability
factors include: equipment size and weight, power consumption,
intelligibility, operational range, latency (i.e., delay time) between
message input at the transmitter and message output at the receiver,
interoperability with other users, complexity of operation, and
requirements for special features like encryption and digital messages.

Evaluating spectrum effectiveness often requires "comparing apples and
oranges." How much should a 25 percent improvement in spectrum
efficiency weigh against a 60 percent increase in cost or a ten percent
decrease in intelligibility? The effectiveness of a proposed change
could be evaluated differently by various users who have developed their
own value of the relative benefits of various factors. Therefore, a
single formula will not serve to calculate the relative effectiveness of
a proposed change as seen by all federal users. For example, users
competing for channels in a crowded urban environment will probably
count spectrum efficiency as more valuable, compared to rural users,
where unused spectrum is more plentiful.

A study of effectiveness must consider broader questions about how the
federal government is using the radio spectrum, including larger-scale
structural and organizational changes, such as shared radio systems.
Implementing a shared federal radio system would be a much more
challenging project than switching to a more spectrum efficient radio
technology. However, a shared federal radio system might favorably
affect a large number of factors that are part of the "effectiveness"
equation, including problems of interoperability between public safety
agencies; spectrum efficiency; meeting the narrowbanding deadlines;
improved radio capabilities (e.g., data, encryption, emergency capacity,
greatly expanded wireless Internet systems, etc.); economies of scale;
cost reduction; and complexity/robustness issues.

Therefore, NTIA has embarked on a multi-phased study of spectrum
efficiency and effectiveness within the federal government land mobile
bands. The first phase of the study, described in this report, analyzes
the present federal land mobile radio (LMR) use of the radio spectrum in
the 162-174 MHz band within a 100-mile radius around Washington, D.C.,
by developing a quantitative model of the signal capacity (SC) of
current federal use of the radio spectrum (described below). The second
phase of the study will be based on the quantitative SC model results
developed in the first phase and will investigate various alternatives
for possible future federal mobile radio systems, including the
possibility of radio systems shared among federal agencies. Phase 2 will
also define the conditions under which improvements could be made,
taking into account such elements as costs, schedules, missions, etc.
Other phases of the overall study will review and evaluate frequency
assignment techniques, equipment standards, and engineering practices
used in the federal government. Since these additional studies will not
be limited to the Washington, D.C. area, and the 162-174 MHz band, they
will be conducted independently from the first two phases.

When considering the possible advantages of replacing current radio
systems with alternative radio system(s), spectrum users and managers
must have realistic information on the services that current systems
provide. Any proposed new system design could address many additional
factors (e.g., projected growth, new digital services, etc.), but as a
minimum, the new system must provide the same level of service
associated with the current systems.

The wide variety of federal mobile radio services needed to be reduced
to a "lowest common denominator" under which all mobile services could
be considered together and summarized in a simple way. The two most
important factors in level of service are geographical availability of
service and the number of users that can be simultaneously served. Other
factors---like the availability of various advanced digital services --
are also important, but at lesser level and were not considered in this
analysis. The resulting signal capacity (SC) model counts the number of
independent radio signals that could be received at a given location by
a hypothetical mobile user and creates a map showing the number of
receivable signals at various locations. The SC model itself is not a
usable description of spectrum efficiency or effectiveness, though it
contains an important part of the geographical functional requirements
that alternative systems must meet.

After considering various possible methods of obtaining a large amount
of quantitative information on current federal mobile radio service
levels, NTIA decided to calculate SC values by analyzing the data that
is currently available in the Government Master File (GMF). When
necessary, the existing GMF data was augmented using operational data
provided by agency representatives. The SC Analysis Program (SCAP)
processed data from the GMF, augmented with additional "function codes"
describing each assignment, to create the SC maps used in this study.

Any alternative future radio system needs to provide at least as much
access to radio signals at each location as shown by these SC maps. The
results of this modeling will help in quantifying the advantages and
disadvantages involved in potential alternative radio system concepts,
as well as providing insights about the best architectures and
technologies to employ, and the circumstances under which maximum
effectiveness could be achieved.

Ongoing federal agency initiatives are investigating the potential for
substantially improving federal radio systems operations by moving from
individual agency mobile radio systems to a single shared system that
includes state-of-the-art technologies. For example, the Integrated
Wireless Network (IWN) is a shared trunked system that is being jointly
designed and built by several agencies within the U.S. Department of
Justice, U.S. Department of the Treasury, and the U. S. Department of
Homeland Security (DHS).

This Phase 1 report contains a description of federal agencies with GMF
assignments in the 162-174 MHz band, with emphasis on their LMR systems
and their use in the Washington, D.C. area. It also describes many of
the mobile radio technologies used by the agencies, and explains the
SCAP algorithms used to convert the GMF data to SC maps. The overall
objective of this portion of the study was to produce a data set and
corresponding analysis as inputs to the Phase 2 work to design possible
future federal mobile radio systems. Therefore, this initial report does
not contain extensive recommendations or conclusions.

This Phase 1 study identifies a wide variety of functions that federal
agencies perform in the 162-174 MHz band in the Washington, D.C. area.
These functions include law enforcement, transportation, natural
resources management, and emergency and disaster relief. There are a
total of 4,761 frequency assignments identified from the GMF within 100
miles of Washington, D.C. Of the 4,761 assignments, 2,816 do not have a
local infrastructure associated with them (i.e. area-wide assignments).
Lacking any specific transmitter location, these 2,816 assignments were
excluded from the analysis since the SC model considers only
transmitters. In addition, all assignments for receivers (including
receive-only sites) were also excluded from the SCAP analysis, as were
numerous special-purpose transmitters whose functions would not
reasonably be included in a future system. The Phase 1 study considered
GMF assignments as of November 2002, which was when this study
commenced. Any subsequent modified assignments related to the bureaus or
agencies that have been incorporated into the DHS were not addressed,
since the DHS was established after the start of this study.

The majority of federal LMR systems in the 162-174 MHz band use analog
voice systems with 25 kHz channel bandwidth. Approximately half of those
systems, including most of the rural systems that serve national parks
and forests as well as less-populated land use areas, use a simple
repeater technology to extend the range of mobile and portable radios.
There is essentially no use of simulcast networks or trunked radio
systems in this frequency band. Most federal use of trunked systems
occurs in the 380-400 MHz and 406-420 MHz bands, where channel plans
simplify the design of trunked systems and shared base stations. Urban
use includes large numbers of receive-only base stations operating as
voting receivers to provide for effective use of lower power portable
radios inside buildings. However, the SCAP model developed for this
study did not consider any aspects of receivers or the base station
receiver networks. In addition, the SCAP model makes no distinction
between various mobile technologies, such as wideband or narrowband,
digital or analog, voice-only or advanced digital services, trunked or
non-trunked, encrypted or un-encrypted, etc.

The SCAP was developed for this study using a Longley-Rice terrain-based
propagation model to predict the coverage of each appropriate
transmitter in the GMF database. This assumes that "coverage" was
defined for this report as all locations having predicted field strength
of at least ten microvolts/meter, calculated at one-mile intervals. The
coverage areas for each transmitter were combined into coverage areas
for networks of transmitters, using different algorithms for different
types of mobile radio technologies and architectures. Figure 1 shows an
example of an SC map for a small number of transmitters for the U.S.
Coast Guard.

![](media/image2.png){width="4.34375in" height="3.8756944444444446in"}

agencies are included in the report. The maps for individual agencies
can also be combined to create maps for groups of agencies; maps for
several combinations of agencies have also been included. The results of
the SCAP model indicate there are 48 federal agencies operating in the
100-mile radius circle from which GMF data was analyzed, using a total
of 866 infrastructure-based transmitters to provide coverage to
mobile/portable users. Out of the total coverage area for which SC
results were calculated, 93 percent of the locations had coverage from
at least one radio signal, counting the signals from all federal
agencies. Ten percent of the locations had coverage from at least 100
independent radio signals, and approximately four percent of the
locations had coverage from at least 200 independent radio signals.
Figure 2 shows that mobile users at some locations near the center of
Washington, D.C., could receive as many as 268 independent signals. In
practice, federal agencies typically use only the radio signals assigned
to their own agencies, which results in far fewer available signals for
most users.

![](media/image3.png){width="4.459722222222222in" height="4.0875in"}

The presence of 268 independent signals in downtown Washington, D.C. can
be related to overall levels of crowding by noting that the 162-174 MHz
band contains about 960 single-frequency channels (assuming 12.5 kHz
channel spacing across 12 MHz of spectrum). However, most federal radio
systems in this band are still using older 25-kHz channel technology
(reducing the number of available frequencies to approximately 480).
Many of the federal systems, including all repeater systems, require a
pair of frequencies for normal operation of one channel. This would
reduce the maximum number of independent channels to about 240. Thus,
the presence of 268 independent signals in downtown Washington is made
possible only because of some simplex-channel operations that require
only a single frequency per channel and some agencies who have already
switched to 12.5 kHz channel operation. This analysis shows that most of
the available channels are already in use for specific functions. It
does not mean that these assigned channels are actually carrying radio
signals 100 percent of the time. Channel occupancy measurements by the
NTIA Radio Spectrum Measurement System (RSMS) are planned for summer
2004. These measurements will provide detailed traffic statistics for
many of these channels, as well as the total traffic loading that
proposed future radio systems would need to support.

The SC maps described above are actually called "peak signal capacity"
(PSC) maps. The PSC maps will be accompanied by a corresponding set of
"average signal capacity" (ASC) maps in this report. The ASC maps show
information similar to the PSC maps, except that the ASC maps contain
data on the number of independent users per square mile that could be
served by the existing analyzed mobile radio systems. The ASC data is
needed so that future alternative radio systems can be designed with
base stations having a range of different coverage areas, where the
required traffic carried by a given base station will scale
proportionally to the coverage area. The Appendix of this report
includes a detailed description of computing and interpreting ASC and
PSC maps.

The results obtained for the Phase 1 SC analysis provide a useful
description of the coverage of current federal radio systems used in the
162-174 MHz band in the Washington, D.C. area. The data that is
summarized in this report in the form of ASC and PSC maps and the
channel occupancy data from the planned RSMS measurements will furnish
an important part of the quantitative basis for the next phase of this
initiative which considers the design of possible future shared radio
systems

In May 2003, President George W. Bush signed an Executive Memorandum to
develop and implement a comprehensive United States Spectrum Policy for
the 21^st^ Century. The initiative was designed to foster economic
growth, ensure national and homeland security, maintain U.S. global
leadership in communications technology development and satisfy other
vital U.S. needs such as public safety, scientific research, federal
transportation infrastructure and law enforcement. The Secretary of
Commerce then established a Federal Government Task Force and initiated
a series of public meetings to address improvements in policies
affecting spectrum use by the Federal Government, State, and local
Governments, and public sector. The recommendations resulting from these
activities were included in a two-part series of reports released by the
Secretary of Commerce in June 2004, under the title *Spectrum Policy for
the 21st Century- The Presidents Spectrum Policy Initiative*. These
reports contain recommendations regarding the efficient use of the radio
spectrum. Since the report contained within was underway prior to the
release of the *Spectrum Policy for the 21st Century- The Presidents
Spectrum Policy Initiative*, it may be necessary for NTIA to modify its
activities under the policy initiative based on the recommendations made
to the President.

#  INTRODUCTION 

##  Background

The National Telecommunications and Information Administration (NTIA),
an agency of the U.S. Department of Commerce, is responsible for
managing federal agency use of the radio spectrum. The NTIA establishes
policies concerning frequency assignment, allocation and use, and
provides the various federal departments and agencies with guidance to
ensure that their conduct of telecommunications activities is consistent
with these policies.[^1] The NTIA also serves under the Executive Branch
as the President\'s principal adviser on telecommunication policies
pertaining to the nation\'s economic and technological advancements and
to the regulation of the telecommunications industry.[^2]

In support of these responsibilities, NTIA has undertaken numerous
spectrum-related studies to: assess spectrum utilization; examine
reallocating government spectrum or relocating federal government
systems; identify existing or potential electromagnetic compatibility
(EMC) problems between systems; provide recommendations for resolving
EMC conflicts; recommend the changes to promote efficient and effective
use of the radio spectrum; and improve the spectrum management process.

Since the radio frequency spectrum is a finite natural resource,
efficient use of this resource must be one of the primary goals of
government, both within the government sector (i.e., federal, state and
local) and within the private/commercial telecom sector. Historically,
efficient use of this spectrum, in the federal government, has been a
process of self-policing, peer review, and regulatory controls. As
demand for spectrum has increased, NTIA and the Federal Communications
Commission (FCC) have examined policies and regulations that require,
promote or facilitate efficient use of the spectrum to ensure adequate
spectrum resources for growth of existing services and available
spectrum for new services.

Spectrum efficiency is one of the cornerstones for obtaining maximum
capacity from the limited frequency spectrum. Although spectrum
efficiency can be defined in many ways, it remains difficult to balance
theoretical efficiency with mission effectiveness, resource management
and other important requirements. For example, the federal government
uses mobile communications in support of congressionally mandated
missions related to public safety and the welfare of life and property,
military tactical services and operations associated with large,
geographically dispersed organizations. Many of these services can and
are being met through commercial service providers, where spectrum
efficiency is inherently included as one of the aspects of a competitive
market. The federal government places heavy reliance on the private
sector in providing telecommunication service for it own use. In order
to emphasize the government's proper role as a user, any proposal
designed to provide needed telecommunication service, which requires the
government to perform any of the "provider" functions, shall be adopted
only if commercial service is:

a.  not available to the user during the time needed;

b.  not adequate from either a technical or operational standpoint; or

c.  significantly more costly.

A non-commercial service approach is acceptable if it will result in
significant savings over an otherwise acceptable commercial service
offering.[^3]

NTIA has an ongoing telecommunication policy regarding spectrum
efficiency consistent with its goals to administer this resource wisely
and stimulate the economic growth of the nation. Key national objectives
are to ensure effective, efficient, and prudent use of the spectrum in
the best interest of the nation, taking care to conserve it for uses
where other means of communication are not available or feasible[^4][^5]
In addition, the process by which NTIA manages the federal government's
use of the spectrum ensures that spectrum is used for the public benefit
in support of the missions and tasks of the federal government. Although
these processes stress efficient and effective use of the spectrum, NTIA
relies heavily on each agency to implement similar policies and ensure
that systems, in their use or by their design, are spectrum efficient.
NTIA has not generally reviewed the details of these agency decisions,
beyond a general review of new systems and the frequency coordination
and assignment processes. The decision as to whether an application or
technology uses too much spectrum, or why an application cannot use a
commercial service or alternate technology that does not consume
spectrum resources, is generally left up to the operating agency which
must ensure the effectiveness of its operations. However, within the
mobile service, specifically land mobile, NTIA has taken a more
aggressive position regarding spectrum efficiency.

In October 1992, Congress directed NTIA to implement a plan for federal
agencies with existing mobile radio systems to use spectrum technologies
that are at least as spectrum efficient and cost effective as readily
available commercial mobile radio systems.[^6] NTIA submitted a plan to
Congress in 1993 outlining the steps NTIA would take to ensure land
mobile spectrum efficiency[^7][^8] The plan resulted in NTIA, with the
advice of the Interdepartment Radio Advisory Committee (IRAC),
developing policies and rules governing all users of the mobile bands
allocated to the federal government on a primary basis. These rules
included a transition to narrowband or equivalent technology,
effectively doubling the number of channels available for future use.
Federal agencies have been struggling through technology, budget and
operational issues in their attempts to implement these rules. One
difficulty is the transition to new digital technology, which is not
necessarily backward compatible with 25 kHz analog operations.

A number of recent events and reports have highlighted the need to
maintain a focus on spectrum efficiency. The results of these activities
offer some insight into current thinking, historical references, and
emerging initiatives concerning spectrum efficiency. These include, but
are not limited to, the NTIA Spectrum Summit, the FCC Spectrum Policy
Task Force, two General Accounting Office (GAO) reports on spectrum
management, and a presidential initiative to move spectrum management
into the twenty-first century.

One of the common objectives expressed in these reports and events is
maximizing spectrum efficiency, especially in the bands used for mobile
communications. Many believe that federal government agencies have fewer
mobile users per unit of spectrum than is true for business, state and
local public safety related, or common-carrier (i.e., cellular phone and
personal communications system (PCS)) applications. As a result, there
are concerns that the federal agencies are not using the spectrum as
efficiently as their private sector counterparts. For example, public
safety users require high reliability and availability with frequency
channels whose traffic loads change drastically with planned or
unplanned events. As a result, since these operations are not in use all
of the time, it could be perceived as inefficient use of the spectrum.

In 1994, NTIA produced a report that enumerated the many well-known ways
to improve the efficiency of mobile radio systems.[^9] These methods
include, but are not limited to, decreasing bandwidth, increasing
geographical frequency reuse and increasing the amount of time that a
given frequency can be used by multiple users. The federal government
has expended considerable effort to ensure that its use of the spectrum
is efficient by adopting many spectrum efficient technologies including:
narrowbanding, sharing, overlaying, and applying new spectrum planning
techniques. Although these methods are well-known in the land mobile
community and NTIA has encouraged their adoption, agencies have not
applied them widely, because the methods may also have substantial
disadvantages. Sometimes the disadvantage is a matter of higher cost
stemming from a requirement to buy new equipment to replace older,
less-efficient systems. Other possible disadvantages can include a
decrease in performance or convenience, in addition to high cost and
mission impact.

Therefore, in this report, an important "measure" regarding new mobile
radio technologies has been consolidated under the title of
"effectiveness." Effectiveness includes spectrum efficiency, usability
and cost factors. Usability factors include: equipment size and weight,
power consumption, intelligibility, operational range, latency (i.e.,
delay time) between message input at the transmitter and message output
at the receiver, interoperability with other users, complexity of
operation, and requirements for special features like encryption and
digital messages.

Evaluating spectrum effectiveness often requires "comparing apples and
oranges." How much should a 25 percent improvement in spectrum
efficiency weigh against a 60 percent increase in cost or a ten percent
decrease in intelligibility? The effectiveness of a proposed change
could be evaluated differently by various users who have developed their
own value of the relative benefits of various factors. Therefore, a
single formula will not serve to calculate the relative effectiveness of
a proposed change as seen by all federal users. For example, users
competing for channels in a crowded urban environment will probably
count spectrum efficiency as more valuable, compared to rural users,
where unused spectrum is more plentiful. The problem however, is that
rural locations do not have adequate coverage due to widely-spaced base
stations.

"Effectiveness" forces planners to evaluate proposed changes against a
much broader and more complete set of criteria. Proposed changes that
benefit a wider range of users are more likely to be adopted and
implemented than those that benefit some users, but which place other
users at a disadvantage.

A study of effectiveness should consider broader questions about how the
federal government is using the radio spectrum and consider whether
larger-scale structural and organizational changes, such as shared radio
systems, could improve both the technical efficiency and effectiveness
of federal radio systems. Implementing a shared federal radio system
would be a much more challenging project than switching to a more
spectrum efficient radio technology. However, a large number of related
factors are part of the "effectiveness" equation, including: large
required expenditures to independently solve problems of
interoperability between public safety agencies (e.g. the E-government
Initiative on Interoperability. (Project SAFECOM); homeland security
(e.g., the Department of Homeland Security (DHS) and the Integrated
Wireless Network (IWN)); spectrum efficiency (e.g., meeting the
narrowbanding deadlines); improved radio capabilities (e.g., data,
encryption, emergency capacity, greatly expanded wireless Internet
systems, etc.); and economies of scale and complexity arguments).

To better understand how the federal agencies use the spectrum and how
to improve the effectiveness of this use, NTIA has undertaken a
multi-phased study of spectrum effectiveness within the federal
government land mobile bands. The first phase of the study, described in
this report, analyzes the present federal use of the radio spectrum in
the 162-174 MHz band in the vicinity of Washington, D.C. by developing a
quantitative model of the "signal capacity" (SC) of current federal use
of the radio frequency spectrum. The second phase will be based on the
quantitative model results developed in the first phase and will explore
various modern radio system alternatives to current federal systems such
as shared federal systems.[^10] Depending on the apparent overall
benefits (i.e., improved effectiveness) identified by the results of
this phase, one or more concepts may be selected for further engineering
and/or eventual large-scale or small-scale implementation (e.g., costs,
requirements). Phase Two will also define the conditions under which the
improvements could be made, taking into account items such as costs,
schedules, and missions. Additional studies of the overall initiative
will consider aspects such as frequency reuse criteria as it relates to
spectrum management and the assignment process as well as spectrum
standards to improve spectrum effectiveness. These additional studies
will be conducted concurrently with Phase Two.

##  Scope of Work

### Overall Objective

The objective is to conduct a multi-phased study of spectrum
effectiveness and efficiency, within a federal government land mobile
band. This effect will determine the improvements or changes that could
be made through technologies, frequency coordination and assignment
practices, standards, policies, and reorganization of communication
architectures and organizations that would increase the effectiveness of
spectrum use and spectrum efficiency to satisfy the future spectrum
requirements of the federal government.

### Specific Objectives

*Phase 1:*

a.  Gather and develop information on current federal government land
    mobile requirements within the 162-174 MHz band within 100 miles of
    Washington, D.C. including:

    -   frequency assignments in the Government Master File (GMF);

    -   the type of radio communication networks (trunked, conventional,
        etc.);

    -   the equipment characteristics (power, bandwidth, nature of and
        quantity of information transfer, etc.);

    -   nature of mission, technical and operating requirements for each
        federal agency (voice, data, availability required, priority,
        etc.);

    -   future plans and spectrum requirements; and

    -   measure of SC of current federal mobile radio systems via
        development of a quantitative model.

b.  Calculate SC results of current federal mobile radio systems, using
    the information obtained in (a).

> *Proposed Phase 2:*

-   The NTIA Radio Spectrum Measurement System (RSMS) will make channel
    occupancy measurements for federal radio systems in the 162-174 MHz
    band during summer 2004. These measurements will be used to
    "calibrate" the geographical SC maps produced in Phase 1, producing
    similar maps expressed in Erlang per hour mobile radio traffic
    statistics.

-   Based on the quantitative SC results developed in Phase 1 and
    calibrated with RSMS traffic measurements, explore various modern
    radio system alternatives to the current federal systems.

-   Define the conditions under which the improvements could be made
    taking into account items such as costs, schedule of transition and
    mission.

###  {#section .unnumbered}

### Other Related Work {#other-related-work .unnumbered}

Other tasks will include:

a.  Review and evaluate the techniques, engineering practices, and
    related policies used in assigning spectrum for federal land mobile
    use, identifying and characterizing the various engineering
    techniques and procedures used in assigning spectrum for land mobile
    use; the improvements that could be made to these techniques and
    procedures to minimize spectrum use and maximize efficiency; and the
    changes required to the policy, procedures, and technical
    engineering (e.g., NTIA Manual, allotment strategies, standards and
    assignment nomination models (such as Spectrum XXI), Annex I
    (Procedure for Evaluating Frequency Proposals), Joint Spectrum
    Management System) necessary to make use of the spectrum more
    efficient and effective;

b.  Review of ongoing industry work in the area of land mobile standards
    to determine if the emission masks and receiver performance
    standards in Chapter 5 of the NTIA Manual need to be updated.

#  PHASE 1 OVERVIEW

##  General

When considering the possible advantages of replacing current smaller
individual-agency radio systems with alternative future larger shared
federal mobile radio system(s), spectrum users and managers must have
realistic information on the services provided by the current systems.
This information serves as a starting point for the design of any new
system. Any system proposed to meet spectrum efficiency requirements
must provide at least as much service as the existing systems and meet
the mission requirements of the agencies. Any proposed alternative
system may include many additional factors (e.g., projected growth), but
as a minimum, spectrum users and managers must ensure these systems are
designed with an awareness of what levels of service are provided by
current systems. Otherwise, they cannot determine if any future
alternative system would provide equivalent service.

The first phase of this study provides quantitative information on
current system operations. Many advanced radio systems provide relative
advantages or disadvantages that depend substantially on certain economy
of scale factors. This is especially true for trunked radio systems, but
such results affect many aspects of calculating peak loading factors. To
compare future alternative systems with current systems, some basic
parameters must be known, such as how many channels are required for
current systems. The following provides an overview of the Phase 1
study, including the information required on current radio systems.

First, to develop a signal capacity analysis program (SCAP), NTIA sought
to understand the mobile radio technologies currently being used by
federal agencies. This SCAP includes SC algorithms to accurately analyze
all of the pertinent radio technologies and architectures whose function
could be included in future shared systems. Equally important was to
identify the radio technologies or functions that could not be
reasonably analyzed with the SCAP or included within future shared
systems. The services of these systems will need to continue to be
provided separate from the SCAP model and future shared systems. Typical
LMR technologies used by federal agencies are described in Section 3.

In addition to understanding the current radio technologies and
architectures, the current agency missions and specific operational
requirements must be understood to supplement the data used in the SCAP.
For example, the SCAP specifically does not include any information on
receivers or the need to use multiple receive-only sites. Similarly, the
SCAP contains no information on agency requirements for encryption,
nationwide coverage, advanced data services. However, all of those
factors will be needed as auxiliary specifications in order to design
future systems. Therefore, NTIA identified and summarized current agency
operations and special characteristics needed to support those
operations. Section 4 includes this summary of current agency operations
and activities.

Previous and ongoing federal studies and programs have mandated or have
encouraged certain technologies and incentives promoting spectrum
efficiency requirements to be used by various federal or non-federal
public safety systems in many radio bands. Section 5 summarizes these
various programs.

The concept of the SCAP is discussed in more detail in Section 6.
Section 7 provides the SC results for each federal agency and for
certain combinations of federal agencies. Section 8 provides a summary
of the findings. The Appendix provides more specific details of the
SCAP.

##  Concept of the Signal Capacity Analysis Program (SCAP)

To study the current level of service that exists for federal radio
systems, NTIA needed to reduce a wide variety of federal mobile radio
services to a "lowest common denominator" under which all mobile
services could be considered together and summarized. The SCAP counts
the number of independent radio signals that could be received by a
mobile user at a given location, summarizing these results in a map of
SC for locations in the Washington, D.C. area. Any alternative future
radio system then will need to provide at least as many radio signals to
a mobile user at any location on the map as the current system does.
This model should help to quantify the advantages and disadvantages
involved in future radio system reorganization, as well as provide
insights into the best architectures and technologies to be employed and
the circumstances under which maximum effectiveness would be achieved.
Ongoing federal agency programs (i.e., IWN) are investigating the
potential of federal radio systems operations being substantially
improved by moving from individual-agency mobile radio systems to single
shared systems that include state-of-the-art technologies.

Any model that is used to characterize the amount of service provided to
federal users by current federal mobile radio systems in the 162-174 MHz
band should reflect several characteristics. The model should: 1)
calculate a quantity closely related to the service delivered to federal
mobile radio users; 2) use only data available within the Government
Master File (GMF); 3) be additive or otherwise allow easy manipulations
to include different agencies or other user populations; 4) be
transparent, in the sense that a given user can identify and verify its
own contribution to the total results; 5) allow easy determination of
anticipated results from prototype or proposed alternative radio
systems, to facilitate comparisons between existing and alternative
systems; and 6) require a minimum number of assumptions that could
drastically change the model results.

The SCAP developed for this study is appropriate for estimating the
amount of service currently used by the federal agencies. In its
simplest form, the SCAP assumes that most federal radio users operate in
a mobile or portable environment and depend on a two-way voice channel
created by a federally-owned base station. Therefore, service can be
quantified by merely counting the number of independent voice channels
available at any given geographical location, assuming that "available"
means sufficient base station signal field strength to be received by a
typical portable LMR radio. The presence of an available signal
transmitted by a base station means that the base station will also have
a receiver that is suitable to receive a signal transmitted by the
mobile unit. The model, however, only counts the number of signals that
the mobile/portable unit can receive. Section 6 provides a more detailed
description of the SCAP.

## Selection of 162-174 MHz Band in the Washington, D.C. area

The 162-174 MHz band was selected for this study because this is the
major band used for federal land mobile radio. The Washington, D.C. area
was chosen because of the high concentration of federal users. Selection
of the frequency band in the Washington, D.C. area provides an
opportunity to: 1) investigate spectrum efficiency solutions in areas
where those solutions are needed most; 2) realize economic savings due
to economies of scale associated with potential solutions; 3) test
solutions delivering required advanced technology capabilities like
encryption and new digital services; and 4) consider a territory with
maximum familiarity on the part of federal spectrum management
personnel. The initial choice to include only the 162-174 MHz band was
intended to minimize the effort required to obtain initial results.

##  Sources of Current Usage Data

To support the development of the SCAP, NTIA considered various methods
for obtaining the information needed to estimate the level of services
for current systems. For example, a detailed survey could be submitted
to federal users to obtain their estimates of current and projected
levels of service from their radio networks. However, a survey of this
type would be difficult and time consuming for many of the agencies,
since agencies may have to survey each independent bureau and coordinate
the results. Furthermore, the individual agencies would each have had to
develop suitable models to describe their own current levels of service,
and NTIA would then have to convert the results of those models to a
common overall model.

Another method would be using the NTIA/Institute for Telecommunication
Sciences (ITS) Radio Spectrum Measurement System (RSMS) to conduct
measurements within the Washington, D.C. area to determine the actual
measured traffic occupancy for all frequencies in the band. A major
concern with the RSMS data would be the time required to make and
analyze such measurements at many sites over a wide geographical area.
Measuring low power and intermittent applications would further
complicate the measurements and the interpretation of their results.
Furthermore, it would probably not be possible to collect and accurately
interpret information on multi-site systems using the same frequencies.

The GMF is another possible source of information. It contains records
of the frequencies assigned to all federal government agencies in the
United States. Although the information contained in the GMF is somewhat
limited, it provides information on federal radios over a wide
geographic range.

After considering various possible methods of obtaining quantitative
information on current federal mobile radio service levels, NTIA decided
to estimate current levels of service by analyzing the data that is
already available in the GMF, using computer modeling to generate maps
showing SC. When necessary, the existing GMF data would be augmented
using additional operational data provided by agency representatives.

To obtain the additional data on agency operations, an informal IRAC
committee was established to assist NTIA personnel in understanding some
of the technical details of agency systems operating in the 162-174 MHz
band within the vicinity of the Washington, D.C. area.

Page 2-4/Blank

#  CHARACTERISTICS OF MOBILE RADIO SYSTEMS

##  General

Many types of radio technologies are represented in the mix of LMR
systems used by federal agencies in the 162-174 MHz band. These various
radio technologies described in this section are to: 1) provide an
understanding of the differences among the various technologies; 2)
understand the specific algorithms used to incorporate each of these
technologies into the SCAP; and 3) determine whether there are system
features that cannot easily be incorporated in the SCAP.

### Simplex radio systems 

A simplex radio system is most likely the simplest type of radio system,
as well as being the first type of system that was widely used by radio
users. In simplex systems, the user transmits and receives on the same
frequency. Figure 3-1 shows a typical simplex radio system, composed of
various mobile radio users, M~1~-M~6~, and a base station, B. A typical
user listens to the traffic, if any, transmitted by the other users, and
the base station, as shown in Figure 3-1A. If a given mobile user wants
to talk with any, or all, of the other users, the user waits until no
other user is speaking, then presses the "push-to-talk" button on the
microphone and talks. This causes the radio to shift from "receive" mode
to "transmit" mode, and the transmitted signal is received by the other
radios tuned to that frequency (e.g., M~5~ is shown transmitting in
Figure 3-1B).

![](media/image4.png){width="5.25in" height="1.8229166666666667in"}

[]{#__RefHeading___Toc71359226 .anchor}Figure 3‑3. Simplex Radio System

Within a simplex radio system base stations are functionally equal to
any of the mobile stations, except that base stations are in fixed
locations, and they typically have more transmitter power and a more
advantageously-placed antenna (e.g., at the top of a high tower near the
communications center). This often gives a high-power, high-elevation
base station the ability to "talk" further than typical low-power, low
elevation mobile stations.

The situation is generally worse for communications between mobile
users, where both the receiving and transmitting locations are lower and
the radio paths between them are much more likely to be blocked by
terrain and other obstacles. In Figure 3-1B, the signal from M~5~ is
shown to not be received by M~3,~ possibly because of terrain blockage
between M~3~ and M~5~, or by M~1,~ possibly because of excessive
distance. Thus, the number of users that can participate in a
conversation may depend greatly on the location of the specific user
that is transmitting. This situation can cause various problems. For
example, in Figure 3-1B, M~3~ and M~5~ may be transmitting at the same
time, each unaware that their messages are interfering with each other
in the receivers of other listeners. A given mobile talker may not know
whether the transmitted message has been received by another mobile
listener. A critical mobile-to-mobile message may need to be relayed to
a distant mobile user by the base station or by an intervening mobile
user.

### Radio Repeater Systems 

Repeater architecture, shown in Figure 3-2, is used especially to solve
some of the problems associated with the limited and variable
mobile-to-mobile communications range that is inherent in the simplex
system. The high tower or mountaintop base station is called a
"repeater" and is labeled with an "R" in Figure 3-2. There are two major
changes from the simplex architecture. First, the repeater, unlike the
base station, does not originate or terminate any messages. Second, the
repeater continuously listens on frequency F~2,~ (dashed blue arrow),
and simultaneously transmits whatever it receives on a second frequency,
F~1,~ (solid red arrow). The mobile units use the same two frequencies
reversed in function, (i.e. mobile units continuously listen on F~1~ and
occasionally transmit on the frequency, F~2~).

![](media/image5.png){width="5.003472222222222in"
height="1.7395833333333333in"}

[]{#__RefHeading___Toc71359227 .anchor}Figure 3‑4. Repeater Architecture

At a given instant (e.g., when mobile user M~5~ is transmitting on
F~2~), the other users, shown in Figure 3-2(A) are listening on
frequency F~1~. These mobile users hear the signal on F~1~ that was
originally transmitted at F~2~ from M~5~ and re-transmitted by the
repeater at F~1~. The important feature of the repeater architecture is
that the ability of mobile users to communicate with each other depends
entirely on how well the mobile users communicate with the repeater,
instead of the often problematic direct path between mobile users.

Since the repeater site is typically chosen to provide low-path-loss
propagation to a large geographic area, the usable mobile-to-repeater
coverage is much greater than typical mobile-to-mobile coverage.
Therefore, even though an intervening hill might prevent M~3~ from
hearing M~5~ directly, they can communicate via the hilltop repeater
site.

A primary user (e.g., a dispatcher at M~3~) does not need to connect
directly to the repeater site, but only needs radio contact with the
repeater site, like any of the mobile users. This encourages placement
of the repeater site on the top of a distant high tower or mountaintop,
rather than being constrained to being close to the physical location of
the communications center (e.g., downtown).

The use of separate transmit and receive frequencies for mobile users
also solves a major equipment design problem, since mobile radios can be
built with the assumption that all possible receive frequencies will be
in one frequency band segment, while all possible transmit frequencies
will be in a separate band segment. This simplifies the design of the
radios, while permitting greater flexibility in tuning among many
possible frequency channels. Simplex radios cannot depend on those
critical design simplifications and traditionally have only a few
channels of operation.

### Mobile Talk-Around Mode 

One disadvantage of the repeater architecture is that all communications
must pass through the repeater. If the repeater site malfunctions or if
mobile units drive out of range of the repeater site, communications
will cease, no matter how close together the mobile units may be to one
another. There are various methods of solving these problems. For
example, in some systems it may be practical to switch to a "talk
around" mode where closely-spaced mobile users switch to a simplex mode
and communicate directly with each other using frequency F~2,~
independent of the base or repeater station. Although such talk-around
operation has all of the range limitations associated with mobile-mobile
simplex operations, it provides a very useful alternative mode that
often extends the useful range of operations outside the normal repeater
range.

### Multi-Site Repeater Systems 

The coverage area served by a single repeater site can be increased by
using multiple repeater sites. A two site example is shown in Figure
3-3. A signal will be repeated by repeater R~1~ if the mobile unit is
within range of repeater R~1~ or by repeater R~2~ if the mobile
transmitter is within range of repeater R~2~. Unfortunately, if a mobile
unit is within range of both R~1~ and R~2~ (e.g., M~5~ in the figure), a
signal will be transmitted by both R~1~ and R~2~. Simultaneous R~1~ and
R~2~ signals that are received at about the same signal strength and
frequency by any mobile users (e.g., M~1~ and M~6~ in the figure) can
cause interference, which prevents the signal from being properly
received. A discussion of simulcast systems, which are specially
designed to prevent this problem, is included in the later paragraphs.
However, some multiple repeater systems attempt to negate this problem,
by locating/adjusting repeaters so they cause a minimum amount of such
interference.

![](media/image6.png){width="3.7645833333333334in"
height="1.6395833333333334in"}

[]{#__RefHeading___Toc71359228 .anchor}Figure 3‑5. Multi-Site Repeaters

One way to avoid this interference problem is to use different transmit
frequencies at the repeater sites. Unfortunately, this solution also
requires that the mobile users adjust their receiver frequencies to
match the transmitted frequency of the local repeater site. This adds
some inconvenience for a mobile user. Another way to avoid simulcast
interference is to add a continuous tone-coded squelch system (CTCSS)
signal to the mobile voice transmission. The various codes that can be
transmitted by CTCSS can be used to "activate" individual repeater
sites, so that only the selected site is caused to repeat the message.
The user would have several selectable channels on the mobile radio,
which all used identical frequencies but transmitted different CTCSS
codes. By selecting a particular channel, the user can select which
repeater site to activate.

The use of different repeater transmitter frequencies, versus the use of
activating different sites with CTCSS codes, gives various operational
advantages and disadvantages. The use of CTCSS codes allows mobile users
to operate everywhere using the same pair of frequencies. This means
that mobile users do not need to continually switch frequencies
depending on their location relative to the various repeater sites. The
use of CTCSS also requires many fewer frequencies. However, if the
repeater sites are used individually (i.e., if an incoming mobile
message received at one site is not simultaneously repeated from all
sites), the use of individual repeater transmit frequencies may allow
more independent messages to be repeated from a set of repeater sites.

### Half-Duplex Radio Systems 

The half-duplex architecture combines elements of the simplex and the
repeater architectures, as shown in Figure 3-4. As with the simplex
system technology, half-duplex technology has a base station talking to
multiple mobile users and receiving signals from these users. Like the
repeater system, a half-duplex system transmits messages from the base
station to the mobile users, Figure 3-4(A), at one frequency, F~1~,
(solid red line) and receives messages, Figure 3-4(B), from mobile users
at another frequency, F~2~, (dashed blue line). The primary functional
difference between half-duplex and repeater architectures is that
half-duplex base stations are directly linked to fixed communications
networks, dispatchers, or a command center with wire-line or radio
links.

![](media/image7.png){width="5.997916666666667in"
height="1.3319444444444444in"}

[]{#__RefHeading___Toc71359229 .anchor}Figure 3‑6. Half-Duplex Radio
System

From a functional point of view, most half-duplex system messages
originate or terminate at the base station, whereas all repeater
messages originate and terminate at a distant mobile user. Since
half-duplex system messages usually originate at the base station,
mobile-to-base frequency F~2~ and base-to-mobile frequency F~1~ do not
necessarily have to simultaneously transmit the same information, which
allows some additional useful modes of operation. Messages can be sent
from the base station to mobile users, with no activity in the
mobile-to-base channel, Figure 3-4(A). Messages sent from the mobile
users can be directed toward only the base station listeners (Figure
3-4(B)) or they can also be simultaneously re-transmitted to all users
on frequency F~1~ (Figure 3-4(C)) like a repeater system. So-called
"full-duplex" capabilities simultaneously use F~1~ and F~2~ to provide
full-time two-way voice communications, without the need for a
push-to-transmit control (i.e., cell phone systems are full-duplex). A
full-duplex capability also provides the ability for a mobile user to
transmit a message to the dispatcher, without waiting for the end of an
ongoing message from the dispatcher. However, many portable/mobile
radios do not have the ability to simultaneously transmit and receive,
so these radios could not provide full-duplex operation.

### Multi-Site Duplex Systems 

Duplex systems tend to be used for some large and high priority systems
(i.e., the Federal Aviation Administration's (FAA) National Radio
Communications System (NRCS)). Multiple duplex base stations can be
combined together into networks, providing a coverage area that
represents the cumulative coverage area of the multiple individual base
stations. Large multi-site duplex systems often have the ability for the
user to enter the system at any base station site to gain access to a
dispatcher at a communications center, to connect to the telephone
system, or connect to another base station coverage area at a distant
location. Although multi-site systems can provide a wide range of
services and coverage area, they often also require a high degree of
user knowledge and attention. For example, each base station will use
different frequencies, and the user must continually change transmit and
receive frequencies when moving from the coverage area of one site to
another site. Similarly, a user might contact a distant user by using a
distant base station to provide the needed radio link; however, this
could only be accomplished if the current location of the distant user
was known so that the correct base station could be selected.

Although a simplex channel provides two-way voice service using only
half as many frequencies needed by a duplex system, the duplex
architectures have some substantial advantages over simplex radios. The
main reason is that, although simplex radios operate well by themselves
for many purposes, they do not operate well within groups of other
similar radios. A simplex radio transceiver must be able to receive at
the same frequency that it transmits. A group of simplex transceivers
(e.g., at a base station shared with 20 other simplex channel users)
would need to have the ability to receive a signal simultaneously with
20 other users transmitting on the same antenna tower at nearby
frequencies. This turns out to be extremely difficult from a
technological basis. Even one nearby (in frequency and location)
transmitter will overload the receiver front-end circuits and prevent
reception, and combinations of transmitters will generate interfering
intermodulation products at many unintended frequencies. Thus, sharing
base station facilities with large numbers of other transmitters is
difficult using simplex technology.

Duplex technology uses different frequency band segments for mobile and
base station transmitters (e.g., the lower half of an LMR band is used
for mobile transmitters and the upper half of the band is used for base
station transmitters, with a fixed frequency separation between the
corresponding base and mobile paired frequencies). This greatly
simplifies the construction of radio transceivers and allows much easier
sharing of base station sites. Repeating the earlier scenario of sharing
a base station with 20 other radio systems means the 20 other
transmitters are now all in a different frequency band from that used by
the receiver, and there are far fewer restrictions on how the base
station can be shared. It is much easier to construct receivers and
transmitters that can tune across a whole band with hundreds of
different frequency pairs (channels). Moreover, this easy sharing and
channel flexibility extends to ad hoc mixtures of radios, such as might
occur when multiple agencies deploy their systems in the vicinity of any
major emergency. When the overall usefulness of simplex and duplex
systems is considered, the greater freedom to use arbitrary duplex
channels for many operational situations is often more important than
the implicit efficiency of the single duplex channel in isolated
circumstances.

### ![](media/image8.jpeg){width="2.4604166666666667in" height="2.5in"}Receive-Only Sites 

Duplex systems may, like repeater systems, have substantial problems
with unequal effective operational ranges for mobile and portable radios
versus the base station site. In many systems where reception is
required for portable radios, especially for portable radios operating
inside buildings, the problem of unequal range is solved by adding
"receive-only" (RO) base stations as shown in Figure 3-5.

These additional RO base stations are located so that a base station
receiver is always within the transmitting range of even lower power
portable radios. Typically, the received audio from each of the receiver
sites, RO and two-way, are transferred to a central point (e.g., the
dispatcher or the associated full-function base station) and the "best
quality" received signal is selected as the only received signal.

### Simulcast Radio Systems 

When it is necessary to provide coverage over a larger geographical area
than can be covered from a single base station, simulcasting can be a
more convenient way to combine the coverage area of multiple base
stations, as shown in Figure 3-6. Simulcast base stations use a duplex
frequency plan at each site, but the same frequency pair, the same
transmit frequency (solid red lines), and the same receive frequency
(dashed blue line), is used at all sites. Unlike multi-site duplex
systems described earlier, simulcast systems allow a mobile user to
operate with a uniform pair of transmit and receive frequencies over the
entire coverage area. The three circles in Figure 3-6 show nominal
coverage areas for each of the three simulcast base stations.

As shown in Figure 3-6, the set of simulcasting sites typically produce
some overlapping coverage areas where a given receiver, e.g., M~3~,
could receive approximately equal usable levels of signal from more than
one base station site. To prevent these multiple signals from
interfering with each other, the relative frequencies and time delays of
these signals must be precisely controlled. This is accomplished by
synchronizing frequencies transmitted at all sites and uniformly
delaying the transmission of signals at each site to compensate for the
relative time delays incurred in transporting the signal to each
transmitter site. In the past, it was quite difficult to synchronize the
frequencies, but now it is relatively simple to use Global Positioning
System (GPS) signals from satellites to synchronize clocks and frequency
sources at multiple sites.

![](media/image9.png){width="4.679861111111111in"
height="2.0430555555555556in"}

[]{#__RefHeading___Toc71359231 .anchor}Figure 3‑8. Simulcast System

Simulcast systems also allow a single frequency, paired with the base
transmitter frequency, to be used for mobile transmitters sending
messages to the simulcast base stations. Typically, the signals received
by each base station are all sent back to the simulcast communications
center, where they are compared and the best signal is sent to the
dispatcher, similar to multiple receive-only sites. As with other duplex
radio systems, any messages received from mobile users may, or may not,
be simultaneously re-transmitted to the rest of the mobile users.

Thus, simulcast systems can provide very convenient duplex radio
services over a much larger multi-site coverage area, using a single
pair of base station transmit and receive frequencies. The simulcast
system allows a simple mobile radio to be used across the full
geographical coverage area without needing to switch frequencies or make
other adjustments.

### Trunked Radio Systems

When there are a large number of users concentrated in a given area
(i.e., urban), and frequency resources are limited, trunked radio
systems are a particularly useful type of half-duplex radio system. The
half-duplex systems concepts demonstrated in figure 3-4 also applies to
trunked radio systems. In trunked radio systems, multiple half-duplex
radio channels are available, but none of them are permanently
associated with a given user or function. Instead, the trunked system
temporarily designates an arbitrary channel for a given user message at
the instant that the user requests a radio channel. The only criterion
for choosing a particular channel is that the channel is currently
available (i.e., not being used by any other user) at the time when the
user requests a channel.

The appeal of trunked radio systems is that each channel of a trunked
radio system can carry considerably more traffic than a similar channel
on a conventional radio system, with no apparent user awareness of the
presence of the other users. If "User A" were sharing a channel with
other users on a conventional radio system, User A would be blocked from
service if any of the other users were currently talking on the shared
channel. For example, if the other users kept the channel busy for 20
percent of the time, User A should expect to find the channel
unavailable for use 20 percent of the time. If User A needed immediate
access to a radio channel at all times, this could be accomplished only
by sharing his channel with no other users (or perhaps only a very few
users). However, if User A were sharing channels on a trunked radio
system having ten channels, for example, where other users kept all of
the channels in use for 20 percent of the time, the blocking situation
is much different. Since User A can be given any one of the ten
channels, User A will be blocked only if all ten channels are
simultaneously in use. The probability of all ten channels being used is
much smaller than the probability that a single "User A" channel is in
use. Therefore, each trunked system channel can carry much more traffic
on average before User A will typically have to wait until other users
stop talking.

Another capability of trunked radio systems is the ability to divide
users into various "talk groups." These talk groups determine which
users receive which messages. In general, each user belonging to a
specific talk group hears the messages addressed to that talk group and
transmits messages to the other members of that talk group. This feature
allows the trunked radio system to divide its many users into various
independent talk groups that match the functional groupings by which
agency missions are accomplished. Additionally, existing talk groups can
be rapidly modified to allow the talk group structures to adapt to new
situations, such as major events or emergencies that require new
cross-agency interoperability and command structures.

Trunked systems become particularly flexible and more powerful when
multiple trunked sites are assembled into networks of trunked systems.
Such networks are quite complex and expensive, but they can have
considerable advantages over single-site trunked radio systems.

However, to provide these services, the capabilities of the individual
trunked base stations must be combined into a system using inter-site
connections, which are often broadband wireline or point-to-point
microwave, and controlled with complex computer/controllers. For
example, when a radio user within the coverage area of one site calls a
talk group that is spread across the coverage areas of multiple sites,
the required communications can be provided only by the unified network.
Among various data that the network requires, for example, is the
approximate current location of each talk group member, so that calls
can be sent out via all of the required base stations. In addition, the
network must know the current talk groups for each user, user radio
capabilities, authorization, and encryption data. This information must
be updated whenever a radio user moves from one base station coverage
area to another, turns their radio off or if it moves temporarily out of
range.

The ability of the intelligent network to connect the sites is important
since the network intelligence is what converts individual base station
capabilities to a system having statewide, nationwide, or possibly even
worldwide, coverage with a wide range of techniques to adapt to highly
variable communications needs. There are also issues about the
reliability and robustness of the network connecting the sites as well
as the ability of base stations to continue critical operations if the
network connections are severed. Since all traffic has to move through
the base station sites, a failure of the links connecting a site to the
control network could render the system completely inoperable. In some
systems, the base stations have independent local operation software
that allows them to act as stand-alone trunked repeaters if the
connections to the network fail. This allows a partial set of
communications capabilities to continue functioning, though it could not
provide capabilities that depend on interconnection to the other
elements of the network.

## Summary

The federal agencies currently operate various types of mobile radio
systems. Most of these systems incorporate the techniques described
previously in this section. These descriptions are useful in
understanding the current operations of the various federal agencies
that are described in Section 4 and in understanding the SC algorithms
described in Section 6 or in Appendix A.

**Page 3-10/Blank**

#  FEDERAL OPERATIONS IN THE 162-174 MHz BAND

##  General

The federal government accommodates non-tactical land mobile operations
in the 162-174 MHz and 406.1-420 MHz bands. These two bands are the most
widely used by the federal agencies. Forty-eight federal agencies are
authorized to operate in the 162-174 MHz band, which makes it one of the
bands most heavily licensed by the federal government. [^11] The
following section provides a summary of the 162-174 MHz band in terms of
allocation usage as well as operational descriptions of the federal
agencies' usage in the Washington, D.C. area as of November 2002, when
the study was initiated. The Department of Homeland Security (DHS) is
not included because the department was not established until March
2003.[^12]

##  Allocation

The NTIA Manual contains the international and national allocations and
footnotes, as shown in Table 4-1, for the 162-174 MHz band. The 162-174
MHz band is allocated on a co-primary basis with the fixed service, and
this band is used for fixed systems in addition to mobile systems,
including fixed point-to-point, fixed point-to-multipoint, maritime, and
aeronautical mobile systems.[^13] Thus, federal land mobile operations
are shared with other federal government services in this band and for
this study. The SC analysis and results are derived from only the land
mobile services.

[]{#__RefHeading___Toc71359286 .anchor}Table 4‑1. International and
National Frequency Allocations and Footnotes for the 162-174 MHz Band

+----------+----------+----------+-----------+-----------+----------+
| 162-174  |          |          |           |           |          |
| MHz      |          |          |           |           |          |
+----------+----------+----------+-----------+-----------+----------+
| Inter    |          |          | United    |           | Remarks  |
| national |          |          | States    |           |          |
| Table    |          |          | Table     |           |          |
+----------+----------+----------+-----------+-----------+----------+
| Region 1 | Region 2 | Region 3 | Federal   | No        | A        |
|          |          |          | G         | n-Federal | uxiliary |
|          |          |          | overnment | G         | Broa     |
|          |          |          |           | overnment | dcasting |
|          |          |          |           |           |          |
|          |          |          |           |           | \(74\)   |
|          |          |          |           |           |          |
|          |          |          |           |           | Private  |
|          |          |          |           |           | Land     |
|          |          |          |           |           | Mobile   |
|          |          |          |           |           | (90)     |
+----------+----------+----------+-----------+-----------+----------+
| 156.     | 156.     |          | 162.0     | 162.0     |          |
| 8375-174 | 8375-174 |          | 125-173.2 | 125-173.2 |          |
|          |          |          |           |           |          |
| FIXED    | FIXED    |          | FIXED     | 5.226 US8 |          |
|          |          |          |           | US11 US13 |          |
| MOBILE   | MOBILE   |          | MOBILE    | US216     |          |
| except   |          |          |           | US223     |          |
| aero     | 5.226    |          | 5.226 US8 | US300     |          |
| nautical | 5.230    |          | US11 US13 | US312     |          |
| mobile   | 5.231    |          | US216     |           |          |
|          | 5.232    |          | US223     |           |          |
| 5.226    |          |          | US300     |           |          |
| 5.229    |          |          | US312     |           |          |
|          |          |          |           |           |          |
|          |          |          | G5        |           |          |
+----------+----------+----------+-----------+-----------+----------+
|          |          |          | 17        | 17        | Private  |
|          |          |          | 3.2-173.4 | 3.2-173.4 | Land     |
|          |          |          |           |           | Mobile   |
|          |          |          |           | FIXED     | (90)     |
|          |          |          |           |           |          |
|          |          |          |           | Land      |          |
|          |          |          |           | mobile    |          |
+----------+----------+----------+-----------+-----------+----------+
|          |          |          | 173.4-174 | 173.4-174 |          |
|          |          |          |           |           |          |
|          |          |          | FIXED     |           |          |
|          |          |          |           |           |          |
|          |          |          | MOBILE    |           |          |
|          |          |          |           |           |          |
|          |          |          | G5        |           |          |
+----------+----------+----------+-----------+-----------+----------+

**[Footnotes Applicable to the Federal Government]{.underline}**

**5.226** -- The frequency 156.8 MHz is the international distress,
safety and calling frequency for the maritime mobile VHF radiotelephone
service.

**US8** -- The use of frequencies 170.475, 171.425, 171.575 and 172.275
MHz east of the Mississippi River, and 170.425, 170.575, 171.475,
172.225 and 172.373 MHz west of the Mississippi River may be authorized
for fixed, land and mobile stations operated by non-federal forest
firefighting agencies. In addition, land stations and mobile stations
operated by non-federal conservation agencies, for mobile relay
operation only, may be authorized to use the frequency 172.275 MHz east
of the Mississippi River and frequency 171.475 MHz west of the
Mississippi River. The use of any of the foregoing nine frequencies
shall be on the condition that no harmful interference will be caused to
government stations.

**US11** -- The use of the frequencies 166.250 and 170.150 MHz may be
authorized to non-government remote pickup broadcast base and land
mobile stations and to non-government base, fixed and land mobile
stations in the public safety radio services.

**US13** -- For the specific purposes of transmitting hydrological and
meteorological data in cooperation with agencies of the federal
government the following frequencies may be authorized to non-government
fixed stations on the condition that harmful interference will not be
caused to government stations:

[MHz]{.underline} [MHz]{.underline} [MHz]{.underline} [MHz]{.underline}

169.4250 170.2250 171.0250 171.8250

169.4375 170.2375 171.0375 171-8375

169.4500 170.2500 171.0500 171.8500

169.4625 170.2625 171.0625 171.8625

169.4750 170.2750 171.0750 171.8750

169.4875 170.2875 171.0875 171.8875

169.5000 170.3000 171.1000 171.9000

169.5125 170.3125 171.1125 171.9125

169.5250 170.3250 171.1250 171.9250

**US216** - The frequencies 150.775 and 150.790, and the bands
152-152.0150, 163.2375-163.2625, 462.9375-463.1875, and
467.9375-468.1875 MHz are authorized for government/non-government
operations in medical radio communications systems.

**US300** -- The frequencies 169.445, 169.505, 170.245, 170.305,
171.045, 171.105, 171.845 and 171.905 MHz are available for wireless
microphone operations on a secondary basis to government and
non-government operations.

**US312** -- The frequency 173.075 MHz may also be authorized on a
primary basis to non-government stations in the Police Radio Service
(with a maximum authorized bandwidth of 20 kHz) for stolen vehicle
recovery systems.

**G5** -- Use by the military services is limited by the provisions
specified in the channeling plans shown in Sections 4.3.7 and 4.3.9 of
the NTIA Manual.

### Use of the 162-174 MHz Band 

The GMF was used as the baseline to obtain agency occupancy data for
this Phase 1 study. The GMF is the U.S. Government's database that
contains a complete listing of government frequency assignments and is
an important tool used for various spectrum management activities. Table
4-2 shows the GMF summary of assignments by station class per agency and
radio service in the 162-174 MHz band as of November 2002.[^14]
Accordingly, these assignments may have been revised, updated, or
expanded as needed to meet changing spectrum management requirements.

[]{#__RefHeading___Toc71359287 .anchor}Table 4‑2. Number of Frequency
Assignments

within a 100 Mile Radius of Washington, D.C.

  ----------------- ---------------------------- ----------------------------- ------------- ------------- ------------------ ------------ --------
                    **Aeronautical**             **Land Mobile**               **Mobile**    **Fixed**     **Experimental**   **TOTALS**   

                    **Mobile Service**           **Service**                   **Service**   **Service**                                   

  **Agriculture**                                23                            8             5                                36           1.9%

  **Commerce**                                   12                            2             168                              182          9.4%

  **Coast Guard**                                4                             10                                             14           0.7%

  **Dept. of                                                                                                                                
  Defense**                                                                                                                                

  **Air Force**                                  51                                          1                                52           2.7%

  **Army**                                       61                                          13                               74           3.8%

  **Navy**          3                            9                                                         29                 41           2.1%

  **Energy**                                     39                                          6                                45           2.3%

  **FAA**                                        41                                          67                               108          5.6%

  **Interior**                                   125                           42            85                               252          13.0%

  **Justice**                                    66                            523           81                               670          34.4%

  **Treasury**                                   197                           19            15                               231          11.8%

  **US Capitol                                   25                                                                           25           1.3%
  Police**                                                                                                                                 

  **US Postal                                    41                                                                           41           2.1%
  Service**                                                                                                                                

  **Veterans                                     30                                                                           30           1.5%
  Affairs**                                                                                                                                

  **Others**                                     133                           1             10                               144          7.4%

  **TOTALS**        3                            857                           605           451           29                 1,945         

                    0.2%                         44.0%                         31.1%         23.2%         1.5%                            100.0%

                                                                                                                                           

                    **[Services]{.underline}**   **[Station                                                                                
                                                 Classes]{.underline}**[^15]                                                               

                                                                                                                                           

                    **Aeronautical Mobile**      **FA, FAD, FAT, MA**                                                                      

                    **Land Mobile**              **FB, FBR, ML, MLP, MLPR,                                                                 
                                                 MLR**                                                                                     

                    **Mobile**                   **FL, FLEC, FLR, MO, MOB,                                                                 
                                                 MOE, MOEB, MOEC, MOP, MOR**                                                               

                    **Fixed**                    **FX, FXD, FXE, FXH, FXHR,                                                                
                                                 FXR**                                                                                     

                    **Experimental**             **XT**                                                                                    
  ----------------- ---------------------------- ----------------------------- ------------- ------------- ------------------ ------------ --------

In the 162-174 MHz band, there are 1,945 specific assignments within a
100 mile radius of Washington, D.C. The majority of the area-specific
assignments are in the land mobile service (44 percent), followed by the
mobile (31.1 percent), fixed (23.2 percent), experimental (1.5 percent)
and aeronautical mobile (0.2 percent). The major users of this band are
U. S. Department of Justice (DOJ), U. S. Department of Interior (DOI),
U. S. Department of the Treasury (Treasury), and U. S. Department of
Commerce (DOC). The location of these assignments is shown in Figure
4-1. Table 4-3 provides a summary count of assignments categorized by
agency/bureau, station class and percentage of total assignments by
bureau. There are also 2,816 area assignments in the band that can
potentially be used at any given time. Table 4-4 shows a summary of area
and statewide assignments by agency.[^16]

![](media/image10.jpeg){width="5.444444444444445in"
height="3.229861111111111in"}

[]{#__RefHeading___Toc71359232 .anchor}Figure 4‑9. Plot of All Agency
Frequency Assignments within a 100 Mile Radius

of Washington, D.C. in the 162-174 MHz Band

[]{#__RefHeading___Toc71359288 .anchor}Table 4‑3. Number of Frequency
Assignments within a 100 Mile Radius of Washington, D.C. (162-174 MHz)

  ------------------------------- ------------------ ---------- ------------- ------------- ------------- ------------------ ------------- ------------
                                                                                                                                           

                                  **Aeronautical**   **Land                   **Mobile**    **Fixed**     **Experimental**   **TOTALS\     
                                                     Mobile**                                                                Assignments % 
                                                                                                                             per Agency**  

  **Agency/Bureau**               **Mobile Service**            **Service**   **Service**   **Service**                                    

  **[Agriculture]{.underline}**   ** **              ** **                    ** **         ** **         ** **              ** **         ** **

  **Animal and Plant Health\      ** **              **7**                    ** **         **2**         ** **              **9**         **25.0%**
  Inspection Service**                                                                                                                     

  **Agriculture Research          ** **              **9**                    **1**         **1**         ** **              **11**        **30.6%**
  Service**                                                                                                                                

  **Region 8**                    ** **              ** **                    **7**         **1**         ** **              **8**         **22.2%**

  **Farm Service Agency**         ** **              **1**                    ** **         ** **         ** **              **1**         **2.8%**

  **Washington Office**           ** **              **2**                    ** **         ** **         ** **              **2**         **5.6%**

  **Office of Inspector General** ** **              **4**                    ** **         **1**         ** **              **5**         **13.9%**

  **TOTALS**                      ** **              **23**                   **8**         **5**         ** **              **36**        ** **

  **[Commerce]{.underline}**                                                                                                                

  **(No Bureau)**                 ** **              ** **                    **2**         ** **         ** **              **2**         **1.1%**

  **National Institute of\        ** **              **9**                    ** **         **2**         ** **              **11**        **6.0%**
  Standards and Technology**                                                                                                               

  **National Weather Service**    ** **              ** **                    ** **         **166**       ** **              **166**       **91.2%**

  **Office of the Secretary**     ** **              **3**                    ** **         ** **         ** **              **3**         **1.6%**

  **TOTALS**                      ** **              **12**                   **2**         **168**       ** **              **182**       ** **

  **[Coast Guard]{.underline}**                                                                                                             

  **Coast Guard District 5**      ** **              ** **                    **9**         ** **         ** **              **9**         **64.3%**

  **Coast Guard Headquarters\     ** **              **1**                    ** **         ** **         ** **              **1**         **7.1%**
  Unit 50**                                                                                                                                

  **Coast Guard Headquarters,\    ** **              **3**                    **1**         ** **         ** **              **4**         **28.6%**
  Washington, D.C.**                                                                                                                       

  **TOTALS**                      ** **              **4**                    **10**        ** **         ** **              **14**        ** **

  **[Dept. of                     ** **              ** **                    ** **         ** **         ** **              ** **         ** **
  Defense]{.underline}**                                                                                                                   

  **Air Force**                   ** **              ** **                    ** **         ** **         ** **              ** **         ** **

  **(No Bureau)**                 ** **              **51**                   ** **         **1**         ** **              **52**        **100.0%**

  **TOTALS**                      ** **              **51**                   ** **         **1**         ** **              **52**        ** **

  **Army**                                                                                                                                  

  **AFMO CONUS**                  ** **              **32**                   ** **         **3**         ** **              **35**        **47.3%**

  **Headquarters**                ** **              **1**                    ** **         ** **         ** **              **1**         **1.4%**

  **Corps of Engineers**          ** **              **5**                    ** **         **5**         ** **              **10**        **13.5%**

  **Military District of          ** **              **23**                   ** **         **5**         ** **              **28**        **37.8%**
  Washington**                                                                                                                             

  **TOTALS**                      ** **              **61**                   ** **         **13**        ** **              **74**        ** **

  **Navy**                                                                                                                                  

  **(No Bureau)**                 **3**              **9**                    ** **         **29**        ** **              **41**        **90.9%**

  **TOTALS**                      **3**              **9**                    ** **         **29**        ** **              **41**        **9.1%**

  **[Energy]{.underline}**                                                                                                                  

  **Headquarters Office**         ** **              **39**                   ** **         **6**         ** **              **45**        **100.0%**

  **TOTALS**                      ** **              **39**                   ** **         **6**         ** **              **45**        ** **

  **[FAA]{.underline}**           ** **              ** **                    ** **         ** **         ** **              ** **         ** **

  **(No Bureau)**                 ** **              ** **                    ** **         **5**         ** **              **5**         **4.6%**

  **FAA Eastern Region**          ** **              **41**                   ** **         **61**        ** **              **102**       **94.4%**

  **FAA Western Pacific Region**  ** **              ** **                    ** **         **1**         ** **              **1**         **0.9%**

  **TOTALS**                      ** **              **41**                   ** **         **67**        ** **              **108**       ** **
  ------------------------------- ------------------ ---------- ------------- ------------- ------------- ------------------ ------------- ------------

Table 4-3. Number of Frequency Assignments within a 100 Mile Radius of
Washington, D.C. (Continued)

  ----------------------------- ------- --------- --------- -------- ------- --------- ------------
  **[Interior]{.underline}**                                                            

  **Geological Survey\          ** **   **1**     ** **     ** **    ** **   **1**     **0.4%**
  Administrative**                                                                     

  **Geological Survey\          ** **   **1**     ** **     ** **    ** **   **1**     **0.4%**
  Biological Resources                                                                 
  Division**                                                                           

  **Geological Survey\          ** **   **1**     ** **     ** **    ** **   **1**     **0.4%**
  National Mapping Division**                                                          

  **Office of the Secretary**   ** **   **8**     ** **     ** **    ** **   **8**     **3.2%**

  **National Park Service\      ** **   **65**    **41**    **51**   ** **   **157**   **62.3%**
  National Capital Field Area**                                                        

  **National Park Service\      ** **   **48**    ** **     **34**   ** **   **82**    **32.5%**
  New England Field Area**                                                             

  **U.S. Fish and Wildlife      ** **   **1**     **1**     ** **    ** **   **2**     **0.8%**
  Service\                                                                             
  CT,DE,D.C.,ME,MD,MA,NH,NY,\                                                          
  PA,RI,VT,VA,WV**                                                                     

  **TOTALS**                    ** **   **125**   **42**    **85**   ** **   **252**   ** **

  **[Justice]{.underline}**     ** **   ** **     ** **     ** **    ** **   ** **     ** **

  **Bureau of Prisons**         ** **   ** **     **1**     ** **    ** **   **1**     **0.1%**

  **Drug Enforcement            ** **   ** **     **3**     ** **    ** **   **3**     **0.4%**
  Administration**                                                                     

  **Federal Bureau of           ** **   **53**    **456**   **62**   ** **   **571**   **85.0%**
  Investigation**                                                                      

  **Immigration and             ** **   **1**     **29**    **13**   ** **   **43**    **6.4%**
  Naturalization\                                                                      
  Service**                                                                            

  **Justice Management          ** **   **8**     ** **     ** **    ** **   **8**     **1.2%**
  Division**                                                                           

  **U.S. Marshals Service**     ** **   **4**     **36**    **6**    ** **   **46**    **6.8%**

  **TOTALS**                    ** **   **66**    **525**   **81**   ** **   **672**   ** **

  **[Treasury]{.underline}**                                                            

  **Bureau of Alcohol, Tobacco\ ** **   **33**    ** **     **4**    ** **   **37**    **16.0%**
  and Firearms**                                                                       

  **U.S. Customs Service**      ** **   **21**    **4**     **1**    ** **   **26**    **11.3%**

  **White House Communications\ ** **   **60**    **15**    ** **    ** **   **75**    **32.5%**
  Agency**                                                                             

  **Departmental Offices**      ** **   **3**     ** **     ** **    ** **   **3**     **1.3%**

  **Bureau of Engraving and     ** **   **1**     ** **     ** **    ** **   **1**     **0.4%**
  Printing**                                                                           

  **Inspector General for Tax\  ** **   **10**    ** **     **4**    ** **   **14**    **6.1%**
  Administration**                                                                     

  **IRS Criminal Investigation  ** **   **5**     ** **     ** **    ** **   **5**     **2.2%**
  Division**                                                                           

  **Integrated Treasury         ** **   **4**     ** **     ** **    ** **   **4**     **1.7%**
  Network**                                                                            

  **U.S. Secret Service**       ** **   **60**    ** **     **6**    ** **   **66**    **28.6%**

  **TOTALS**                    ** **   **197**   **19**    **15**   ** **   **231**   ** **

  **[U.S. Capitol                                                                       
  Police]{.underline}**                                                                

  **(No Bureau)**               ** **   **25**    ** **     ** **    ** **   **25**    **100.0%**

  **TOTALS**                    ** **   **25**    ** **     ** **    ** **   **25**    ** **

  **[U.S. Postal                                                                        
  Service]{.underline}**                                                               

  **Postal Inspection Service** ** **   **13**    ** **     ** **    ** **   **13**    **31.7%**

  **Mail Processing and         ** **   **28**    ** **     ** **    ** **   **28**    **68.3%**
  Distribution**                                                                       

  **TOTALS**                    ** **   **41**    ** **     ** **    ** **   **41**    ** **

  **[Veterans                                                                           
  Affairs]{.underline}**                                                               

  **National Cemetery           ** **   **4**     ** **     ** **    ** **   **4**     **13.3%**
  Administration**                                                                     

  **VA Central Office**         ** **   **3**     ** **     ** **    ** **   **3**     **10.0%**

  **Veterans Health             ** **   **23**    ** **     ** **    ** **   **23**    **76.7%**
  Administration**                                                                     

  **TOTALS**                    ** **   **30**    ** **     ** **    ** **   **30**    ** **
  ----------------------------- ------- --------- --------- -------- ------- --------- ------------

**Table 4-3. Number of Frequency Assignments within a 100 Mile Radius of
Washington, D.C. (Continued)**

  -------------------------------- ------------------ ------------- ------------- ------------- ------------------ ------------- ------------
                                   **Aeronautical**   **Land        **Mobile**    **Fixed**     **Experimental**   **TOTALS\     
                                                      Mobile**                                                     Assignments % 
                                                                                                                   per Agency**  

  **Other Agencies & Bureaus**     **Mobile Service** **Service**   **Service**   **Service**                                    

  **[Administrative Office of the\ ** **              ** **         ** **         ** **         ** **              ** **         ** **
  United States                                                                                                                  
  Courts]{.underline}**                                                                                                          

  **(No Bureau)**                  ** **              **7**         ** **         ** **                            **7**         **100.0%**

  **TOTALS**                       ** **              **7**         ** **         ** **         ** **              **7**         ** **

  **[Broadcasting Board of         ** **              ** **         ** **         ** **         ** **              ** **         ** **
  Governors]{.underline}**                                                                                                       

  **(No Bureau)**                  ** **              **2**         **1**         ** **                            **3**         **100.0%**

  **TOTALS**                       ** **              **2**         **1**         ** **         ** **              **3**         ** **

  **[Consumer Products Safety\     ** **              ** **         ** **         ** **         ** **              ** **         ** **
  Commission]{.underline}**                                                                                                      

  **(No Bureau)**                  ** **              **1**         ** **         ** **                            **1**         **100.0%**

  **TOTALS**                       ** **              **1**         ** **         ** **         ** **              **1**         ** **

  **[Environmental Protection                                                                                                     
  Agency]{.underline}**                                                                                                          

  **(No Bureau)**                  ** **              **4**         ** **         ** **         ** **              **4**         **100.0%**

  **TOTALS**                       ** **              **4**         ** **         ** **         ** **              **4**         ** **

  **[FCC]{.underline}**            ** **              ** **         ** **         ** **         ** **              ** **         ** **

  **Field Operations Bureau**      ** **              **7**         ** **         ** **                            **7**         **100.0%**

  **TOTALS**                       ** **              **7**         ** **         ** **         ** **              **7**         ** **

  **[General Services                                                                                                             
  Administration]{.underline}**                                                                                                  

  **(No Bureau)**                  ** **              **13**        ** **         ** **         ** **              **13**        **68.4%**

  **Office of Federal Supplies\    ** **              **1**         ** **         ** **         ** **              **1**         **5.3%**
  and Services**                                                                                                                 

  **Office of Federal Protection\  ** **              **1**         ** **         ** **         ** **              **1**         **5.3%**
  and Safety**                                                                                                                   

  **Office of Information\         ** **              **1**         ** **         ** **         ** **              **1**         **5.3%**
  Resources Management**                                                                                                         

  **Public Buildings Service**     ** **              **3**         ** **         ** **         ** **              **3**         **15.8%**

  **TOTALS**                       ** **              **19**        ** **         ** **         ** **              **19**        ** **

  **[Government Printing           ** **              ** **         ** **         ** **         ** **              ** **         ** **
  Office]{.underline}**                                                                                                          

  **(No Bureau)**                  ** **              **1**         ** **         ** **                            **1**         **100.0%**

  **TOTALS**                       ** **              **1**         ** **         ** **         ** **              **1**         ** **

  **[Health and Human                                                                                                             
  Services]{.underline}**                                                                                                        

  **National Institutes of         ** **              **9**         ** **         ** **         ** **              **9**         **64.3%**
  Health**                                                                                                                       

  **Office of the Inspector        ** **              **1**         ** **         ** **         ** **              **1**         **7.1%**
  General**                                                                                                                      

  **Substance Abuse & Mental\      ** **              **3**         ** **         **1**         ** **              **4**         **28.6%**
  Health Administration**                                                                                                        

  **TOTALS**                       ** **              **13**        ** **         **1**         ** **              **14**        ** **

  **[House of                      ** **              ** **         ** **         ** **         ** **              ** **         ** **
  Representatives]{.underline}**                                                                                                 

  **(No Bureau)**                  ** **              **2**         ** **         ** **                            **2**         **100.0%**

  **TOTALS**                       ** **              **2**         ** **         ** **         ** **              **2**         ** **

  **[Housing and Urban                                                                                                            
  Development]{.underline}**                                                                                                     

  **(No Bureau)**                  ** **              **8**         ** **         ** **         ** **              **8**         **100.0%**

  **TOTALS**                       ** **              **8**         ** **         ** **         ** **              **8**         ** **

  **[International Trade           ** **              ** **         ** **         ** **         ** **              ** **         ** **
  Commission]{.underline}**                                                                                                      

  **(No Bureau)**                  ** **              **1**         ** **         ** **                            **1**         **100.0%**

  **TOTALS**                       ** **              **1**         ** **         ** **         ** **              **1**         ** **

  **[Department of                                                                                                                
  Labor]{.underline}**                                                                                                           

  **(No Bureau)**                  ** **              **4**         ** **         ** **         ** **              **4**         **100.0%**

  **TOTALS**                       ** **              **4**         ** **         ** **         ** **              **4**         ** **
  -------------------------------- ------------------ ------------- ------------- ------------- ------------------ ------------- ------------

**Table 4-3. Number of Frequency Assignments within a 100 Mile Radius of
Washington, D.C. (Continued)**

  ------------------------------- ---------------------------- -- ------- ------------------------ -------- ------- ------- ------- -------- ---- ------------
  **[National Aeronautical and                                                                                                                     
  Space Admin.]{.underline}**                                                                                                                     

  **Goddard Space Flight Center**                                 ** **                            **1**    ** **   **1**   ** **   **2**         **40.0%**

  **NASA Headquarters**                                           ** **                            **1**    ** **   ** **   ** **   **1**         **20.0%**

  **Marshall Space Flight                                         ** **                            **2**    ** **   ** **   ** **   **2**         **40.0%**
  Center**                                                                                                                                        

  **TOTALS**                                                      ** **                            **4**    ** **   **1**   ** **   **5**         ** **

  **[National Security                                            ** **                            ** **    ** **   ** **   ** **   ** **         ** **
  Agency]{.underline}**                                                                                                                           

  **(No Bureau)**                                                 ** **                            **2**    ** **   ** **           **2**         **100.0%**

  **TOTALS**                                                      ** **                            **2**    ** **   ** **   ** **   **2**         ** **

  **[National Gallery of                                          ** **                            ** **    ** **   ** **   ** **   ** **         ** **
  Art]{.underline}**                                                                                                                              

  **(No Bureau)**                                                 ** **                            **4**    ** **   ** **           **4**         **100.0%**

  **TOTALS**                                                      ** **                            **4**    ** **   ** **   ** **   **4**         ** **

  **[National Labor Relations                                     ** **                            ** **    ** **   ** **   ** **   ** **         ** **
  Board]{.underline}**                                                                                                                            

  **(No Bureau)**                                                 ** **                            **1**    ** **   ** **           **1**         **100.0%**

  **TOTALS**                                                      ** **                            **1**    ** **   ** **   ** **   **1**         ** **

  **[Nuclear Regulatory                                           ** **                            ** **    ** **   ** **   ** **   ** **         ** **
  Commission]{.underline}**                                                                                                                       

  **(No Bureau)**                                                 ** **                            **3**    ** **   ** **           **3**         **100.0%**

  **TOTALS**                                                      ** **                            **3**    ** **   ** **   ** **   **3**         ** **

  **[U.S. Senate]{.underline}**                                   ** **                            ** **    ** **   ** **   ** **   ** **         ** **

  **(No Bureau)**                                                 ** **                            **8**    ** **   ** **           **8**         **100.0%**

  **TOTALS**                                                      ** **                            **8**    ** **   ** **   ** **   **8**         ** **

  **[Social Security                                              ** **                            ** **    ** **   ** **   ** **   ** **         ** **
  Administration]{.underline}**                                                                                                                   

  **(No Bureau)**                                                 ** **                            **2**    ** **   ** **           **2**         **100.0%**

  **TOTALS**                                                      ** **                            **2**    ** **   ** **   ** **   **2**         ** **

  **[State                                                                                                                                         
  Department]{.underline}**                                                                                                                       

  **(No Bureau)**                                                 ** **                            **10**   ** **   ** **   ** **   **10**        **90.9%**

  **Office of Information\                                        ** **                            **1**    ** **   ** **   ** **   **1**         **9.1%**
  Resource Management**                                                                                                                           

  **TOTALS**                                                      ** **                            **11**   ** **   ** **   ** **   **11**        ** **

  **[U.S. Supreme                                                                                                                                  
  Court]{.underline}**                                                                                                                            

  **(No Bureau)**                                                 ** **                            **8**    ** **   **3**   ** **   **11**        **100.0%**

  **TOTALS**                                                      ** **                            **8**    ** **   **3**   ** **   **11**        ** **

  **[Smithsonian]{.underline}**                                                                                                                    

  **(No Bureau)**                                                 ** **                            **13**   ** **   **5**   ** **   **18**        **100.0%**

  **TOTALS**                                                      ** **                            **13**   ** **   **5**   ** **   **18**        ** **

  **[Department of                                                                                                                                 
  Transportation]{.underline}**                                                                                                                   

  **Office of the Secretary**                                     ** **                            **8**    ** **   ** **   ** **   **8**         **100.0%**

  **TOTALS**                                                      ** **                            **8**    ** **   ** **   ** **   **8**         ** **

                                  **[Services]{.underline}**              **[Station                                                              
                                                                          Classes]{.underline}**                                                  
                                                                          [^17]                                                                   

                                  **Aeronautical Mobile**                 **FA, FAD, FAT, MA**                                                    

                                  **Land Mobile**                         **FB, FBR, ML, MLP,                                                     
                                                                          MLPR, MLR**                                                             

                                  **Mobile**                              **FL, FLEC, FLR, MO,                                                    
                                                                          MOB, MOE, MOEB, MOEC,                                                   
                                                                          MOP, MOR**                                                              

                                  **Fixed**                               **FX, FXD, FXE, FXH,                                                    
                                                                          FXHR, FXR**                                                             

                                  **Experimental**                        **XT**                                                                  
  ------------------------------- ---------------------------- -- ------- ------------------------ -------- ------- ------- ------- -------- ---- ------------

[]{#__RefHeading___Toc71359289 .anchor}Table 4‑4. Nationwide (US&P, USA,
and US) and Statewide Assignments by Agency

  ----------------- ---------------------------- ----------------------------- -------------- ------------- ------------- ------------ --------
                    **Aeronautical**             **Land Mobile**               **Maritime**   **Mobile**    **Fixed**     **TOTALS**   

                    **Mobile Service**           **Service**                   **Mobile       **Service**   **Service**                
                                                                               Service**                                               

  **Agriculture**   7                            98                                           138           61            304          10.8%

  **Commerce**                                   27                                           11            30            68           2.4%

  **Coast Guard**                                2                             3              8             15            28           1.0%

  **Dept. of                                                                                                                            
  Defense**                                                                                                                            

  **Air Force**                                  4                                                                        4            0.1%

  **Army**                                       10                                                         19            29           1.0%

  **Navy**                                       3                                                                        3            0.1%

  **Energy**        10                           59                                           26            17            112          4.0%

  **FAA**           2                            12                                           1             2             17           0.6%

  **Interior**      2                            51                            1              1,032         170           1,256        44.6%

  **Justice**       2                            85                                           279           41            407          14.5%

  **Treasury**                                   304                                          55                          359          12.7%

  **U.S. Capitol                                 2                                                                        2            0.1%
  Police**                                                                                                                             

  **U.S. Postal                                  30                                                         43            73           2.6%
  Service**                                                                                                                            

  **Veterans                                     31                                                                       31           1.1%
  Affairs**                                                                                                                            

  **Others**        14                           92                            1              11            5             123          4.4%

  **TOTALS**        37                           810                           5              1,561         403           2,816         

                    1.3%                         28.8%                         0.2%           55.4%         14.3%                      100.0%

                                                                                                                                       

                                                                                                                                       

                    **[Services]{.underline}**   **[Station                                                                            
                                                 Classes]{.underline}**[^18]                                                           

                                                                                                                                       

                    **Aeronautical Mobile**      **FA, FAD, FAT, MA**                                                                  

                    **Land Mobile**              **FB, FBR, ML, MLP, MLPR,                                                             
                                                 MLR**                                                                                 

                    **Maritime Mobile**          **FC, FCB, FCD, MS, MSD, MSP,                                                         
                                                 OD, OE**                                                                              

                    **Mobile**                   **FL, FLEC, FLR, MO, MOB,                                                             
                                                 MOE, MOEB, MOEC, MOP, MOR**                                                           

                    **Fixed**                    **FX, FXD, FXE, FXH, FXHR,                                                            
                                                 FXR**                                                                                 
  ----------------- ---------------------------- ----------------------------- -------------- ------------- ------------- ------------ --------

##  Operational Description of Each Agency's LMR Operations

Federal agencies operating in 162-174 MHz band have various functions
that include law enforcement, transportation, natural resource
management, and emergency and disaster relief. How each agency achieves
these functions is based on mission and operational requirements. Not
all of the agencies' primary missions are concentrated in urban areas.
For example, the Departments of Interior and Agriculture are more
concentrated in the rural areas where their missions dictate the
protection and preservation of large expanses of land such as the
national parks and forests. Therefore, some agencies or bureaus may not
be listed in Table 4-3 because they do not have any frequency
assignments in the study area. The following subsections discuss the
general mission, current use, and future plans for each agency that has
assignments in the 162-174 MHz band within the study area. The
information presented may include inputs provided by the various federal
agencies.

### United States Department of Agriculture (USDA)

The USDA's mission is to enhance the quality of life for the American
people by supporting production of agriculture by: ensuring a safe,
affordable, nutritious, and accessible food supply; caring for
agricultural, forest, and range lands; supporting sound development of
rural communities; providing economic opportunities for farm and rural
residents; expanding global markets for agricultural and forest products
and services; and working to reduce hunger in America and throughout the
world.[^19] The USDA has two distinct areas of operations within the 100
mile radius around Washington, D.C., as shown in Figure 4-2. These areas
are: Washington, D.C., for headquarters operations, and the Blue Ridge
Mountain area for the U. S. Forest Service, each of which is described
below. A list of the assignments is shown in Table 4-3.

**Headquarters**

The USDA's Washington, D.C. area current operations consist of a series
of half-duplex and simplex wideband (25 kHz bandwidth) analog mobiles
and hand-helds with repeaters used to extend the range of the networks.
USDA's headquarters nets are used primarily for in-building security and
the inspection bureau. USDA's headquarters future communications will be
expanding to a narrowband (12.5 kHz bandwidth) digital, multi-cast
system, utilizing numerous CTCSS activated repeaters throughout the
Washington, D.C. area. This new system will be Project
25/Telecommunications Industry Association 102 (P25/TIA 102) compliant
and incorporate voice over Internet protocol (VoIP) technology.[^20]

####  {#section-1 .unnumbered}

####  {#section-2 .unnumbered}

#### U.S. Forest Service {#u.s.-forest-service .unnumbered}

The U.S. Forest Service is in the process of upgrading their current
analog wideband system in the George Washington and Jefferson National
Forests (a large part of this forest is in the study area). The U.S.
Forest Service is upgrading its current operations to an analog
narrowband system utilizing tone-code squelch enabled repeaters. All
U.S. Forest Service district offices will be tied to the supervisor's
office via a T-1 landline and system control and dispatch will be
performed using radio control over Internet Protocol (IP) technology.

![](media/image11.jpeg){width="5.444444444444445in"
height="3.3229166666666665in"}

[]{#__RefHeading___Toc71359233 .anchor}**Figure 4‑10. Plot of USDA
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz band**

### United States Department of Commerce (DOC)

The DOC mission is to promote job creation, economic growth, and
improved living standards for all Americans by working in partnership
with business, universities, communities, and workers to build for the
future and promote U.S. competitiveness in the global marketplace by
strengthening and safeguarding the nation's economic infrastructure, and
keeping America competitive with cutting-edge science and
technology.[^21]

The DOC operates a variety of radio communications systems for weather
data dissemination, National Oceanic and Atmospheric Administration
(NOAA) Weather Radio (NWR), Emergency Managers Weather Information
Network, as well as the more conventional systems found in most federal
agencies. Many of these systems operate in bands other than the
government Very High Frequency (VHF) band of 162‑174 MHz. However, the
DOC has the fourth largest amount of assignments in the Washington, D.C.
area, with 182 assignments as shown in Table 4-3. The location of the
GMF assignments is shown in Figure 4-3.

The DOC has two bureaus -- the National Institute of Standards and
Technology (NIST) and the National Weather Service (NWS) -- that have
frequency assignments in the outlined area and this band. The NWS has 74
assignments and NIST has nine, which are further described below. In
addition, DOC has three assignments for the Office of the Secretary for
the Silver Spring office and two other assignments in Baltimore.

**National Institute of Standards and Technology (NIST)**

Of NIST's nine assignments, three are for police/fire/medical emergency
communications, two for direct support of research and one for paging,
and all are on or in the vicinity of the Gaithersburg campus. The other
three serve to coordinate transportation, two transmitting in
Washington, D.C., and one in Gaithersburg, Maryland. All operations are
currently 25 kHz analog mobile and handheld radios. None of the
operations use repeaters.

**National Weather Service (NWS)**

Many NWS assignments, both in and outside the Washington, D.C. area are
associated with the collection and dissemination of meteorological
information. These include

NWR stations, which operate continuously on one of seven frequencies
(162.40‑162.55 MHz) allotted for this use. This is a transmit-only
broadcast type network. The Remote Atmospheric Monitoring and
Observation System stations operate along U.S. coasts 24 hours a day on
163.325 and 163.350 MHz and report tide and other ocean data to central
collection points. The hydrological stations operate 24 hours to collect
such data as cumulative rainfall and rain rate, snow depth and stream
height, typically at unmanned and remote locations. There are 60
hydrological assignments on the frequencies 169.425, 169.4375, 169.475,
169.5, 170.25, 171.1125 and 171.925 MHz.

DOC's future plans indicate a one-for-one swap out of narrowband
equipment for their current wideband radios. Some areas, such as the DOC
security division, have already converted to narrowband analog
operations.

![](media/image12.jpeg){width="5.444444444444445in"
height="3.2041666666666666in"}

[]{#__RefHeading___Toc71359234 .anchor}Figure 4‑11. Plot of DOC
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band

### United States Coast Guard (USCG)

The USCG is a military, multi-mission, maritime service and one of the
nation's five Armed Services. Its mission is to protect the public, the
environment, and U.S. economic interests -- in the nation's ports and
waterways, along the coast, on international waters, or in any maritime
region as required to support national security.[^22]

The USCG has 14 assignments, as shown in Table 4-3, in the 162-174 MHz
band, within the Washington, D.C. area. Figure 4-4 shows the location of
those assignments. The USCG typically operates simplex, data encryption
standard (DES), systems primarily for firefighting and security. The
USCG has eight sites in the study area with all being fixed/mobile law
enforcement or handheld building security. Currently, all channels are
wideband (25 kHz); however, all USCG handheld and mobile radios are
capable of narrowband analog and digital operation when required. The
USCG is adding the 162‑174 MHz and 406.1‑420 MHz bands to their
short-range Rescue 21 (R-21) communication system (talk‑in coverage out
to 20 miles from shore). R-21 will be capable of operating on the 40
discrete frequencies set aside in the VHF and UHF bands for
interoperability between law enforcement and public safety organizations
during disasters and emergencies.[^23] This will allow the USCG to
communicate with federal, state, and local agencies operating on agency
specific frequencies within the VHF (150.8--174 MHz) and UHF (406.1--420
MHz) frequency range. R-21 will be a P25/TIA 102 compliant digital
narrowband system with console-to-console patch capability that can be
used to link communications between the USCG and other federal, state,
and local agencies that do not operate within R-21 frequency bands or
use non-interoperable communication systems.

![](media/image13.jpeg){width="5.444444444444445in"
height="3.3743055555555554in"}

[]{#__RefHeading___Toc71359235 .anchor}**Figure 4‑12. Plot of USCG
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band**

### United States Department of Defense (DOD)

The mission of the DOD is to defend United States territory and any
occupied areas, overcome any aggressor that imperils our nation's peace
and security, maintain freedom of the seas, stabilize or contain
international disturbances, and defend the United States through control
and exploitation of air and space.[^24] The DOD is comprised of the four
military branches: the Army, Navy, Marine Corps, and Air Force. DOD's
presence in the 162-174 MHz band is limited to base security (law
enforcement), fire, and emergency medical services. Table 4-3 shows a
breakdown of assignments by military branch and Figure 4-5 shows the
location of those assignments for the Washington, D.C. area. The systems
are typically wideband analog simplex or half-duplex channels using
repeaters, where necessary, to extend the range of the net. On some
bases, the Army has used cross-band repeaters to provide
interoperability between security forces operating in different bands.

![](media/image14.jpeg){width="5.444444444444445in"
height="3.3229166666666665in"}

[]{#__RefHeading___Toc71359236 .anchor}**Figure 4‑13. Plot of DOD
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band**

The Army is developing a P25/TIA 102 compliant narrowband digital
trunked system in the 380-400 MHz band to replace most systems currently
in the 162-174 MHz band. Phase 1 of the Regional Concept 2005+ plan is
tentatively scheduled to become operational by the end of 2004.[^25] The
system will include all branches of the service and will expand
region-by-region to eventually interconnect military installations
throughout the United States.

### United States Department of Energy (DOE)

The DOE's mission is to advance the national and economic security of
the United States; promote scientific and technological innovation in
support of that mission; and ensure the environmental cleanup of the
national nuclear weapons complex.[^26]

The DOE has 45 assignments, as shown in Table 4-3, in the Washington,
D.C. area. Figure 4-6 shows the location of those assignments. The DOE
already utilizes digital narrowband base stations, mobiles and portables
to support a multi-channel force protection network between the
headquarters building in Washington, D.C. and Germantown, Maryland. Each
site operates on an independent pair of frequencies but can be linked
via radio frequency (RF) to each other. This allows each site to have
control of the Force Protection network. The network nominally operates
in the digital narrowband mode, but has, on occasion, required
encryption operation in wideband analog or digital modes. The DOE has
other two-way repeater systems, a simulcast paging system, and simplex
radios which are going to be gradually replaced with analog narrowband
radios, due to the higher cost of digital narrowband equipment.

![](media/image15.jpeg){width="5.356944444444444in"
height="3.2465277777777777in"}

[]{#__RefHeading___Toc71359237 .anchor}**Figure 4‑14. Plot of DOE
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band**

### Federal Aviation Administration (FAA)

The mission of the FAA is to provide a safe, secure, and efficient
global aerospace system that contributes to national security and the
promotion of U.S. aerospace safety. "As the leading authority in the
international aerospace community, the FAA is responsive to the dynamic
nature of customer needs, economic conditions, and environmental
concerns."[^27]

The FAA has 108 assignments, as shown in Table 4-3, in the Washington,
D.C. area. Figure 4-7 shows the location of these assignments.
Eighty-five percent of the FAA's assignments are dedicated to meeting
its nationwide land mobile requirements through its Command, Control and
Communications (C3) program. Previously called the National Radio
Communications System (NRCS), this conventional VHF/FM system is used to
manage, operate and restore the National Airspace System in support of
FAA, United States Department of Transportation (DOT), and DOD functions
during national disasters and security emergencies. Also, this system
provides daily support for airways facilities technicians, civil
aviation security agents, air traffic administration, and flight
standards. During local, regional, or national disasters or emergencies,
field personnel use the network for command and control missions. The
NCRS/C3 is not confined to urban areas or airports, but covers a wide
territory to reach remote FAA facilities such as radars, microwave
radios, and other navigation/communications facilities.

Currently, the FAA is upgrading and expanding its existing equipment to
meet the NTIA 2005 narrowband mandate and provide greater command and
control support in the aftermath of the events of September 11, 2001.
Older, wideband analog radios are being replaced with new digital
systems. Primarily, the FAA is replacing current repeaters and base
stations on a one-to-one basis, using most existing frequency
authorizations. In addition, the old NRCS frequency channel plan will
remain the basis of the new C3 program. However, due to the need for
expansion and changes in frequency allotments over the past two decades,
there will be some alterations in geographical location and frequencies.

![](media/image16.jpeg){width="5.447916666666667in"
height="3.1458333333333335in"}

[]{#__RefHeading___Toc71359238 .anchor}**Figure 4‑15. Plot of FAA
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band**

### United States Department of Homeland Security (DHS)

The DHS was created in March 2003, with its primary mission to protect
the nation against further terrorist attacks.[^28] Component agencies
will analyze threats and intelligence, guard our borders and airports,
protect our critical infrastructure, and coordinate the response of our
nation for future emergencies. Besides providing a better-coordinated
defense of the homeland, DHS is also dedicated to protecting the rights
of American citizens and enhancing public services, such as natural
disaster assistance and citizenship services, by dedicating offices to
these important missions.[^29] The DHS is a consolidation of agencies
and bureaus from various departments, including: The Immigration and
Naturalization Service (INS) (DOJ), The U.S. Customs Service (Customs)
(Treasury), The Transportation Security Administration (TSA) (DOT),
Federal Law Enforcement Training Center (Treasury), Animal and Plant
Health Inspection Service (USDA), Office for Domestic Preparedness
(DOJ), The Federal Emergency Management Agency (FEMA), Strategic
National Stockpile and the National Disaster Medical System (Health and
Human Services), Nuclear Incident Response Team (DOE), Domestic
Emergency Support Teams (DOJ), National Domestic Preparedness Office
(FBI), Chemical Biological Radiology and Nuclear Countermeasures
Programs (DOE), Environmental Measurements Laboratory (DOE), National
Biological Warfare Defense Analysis Center (DOD), Plum Island Animal
Disease Center (USDA), Critical Infrastructure Assurance Office (DOC),
Federal Computer Incident Response Center (Government Service
Administration), National Communications System (DOD), National
Infrastructure Protection Center (Federal Bureau of Investigation
(FBI)), Energy Security and Assurance Program (DOE), the United States
Secret Service (USSS) (Treasury) and the USCG (DOT).[^30] Although the
GMF assignments from the various agencies have not been officially
reassigned to DHS, as of November 2002, the department has the potential
to become the largest user in the Washington, D.C. area in the 162-174
MHz band. DHS plans to join the IWN with Justice and Treasury as they
change their legacy systems over to narrowband. For the purpose of this
study, no GMF assignment records have been re-designated to DHS but
remained under their previous departments or agencies.

### United States Department of the Interior (DOI)

The DOI is the nation's principal conservation agency. Its mission is to
protect America's treasures for future generations, provide access to
our nation's natural and cultural heritage, offer recreation
opportunities, honor our trust responsibilities to American Indians and
Alaska Natives and our responsibilities to island communities, conduct
scientific research, provide wise stewardship of energy and mineral
resources, foster sound use of land and water resources, and conserve
and protect fish and wildlife.[^31] Within the United States, the DOI
has radio communications requirements in support of the National Park
Service, Bureau of Land Management, Fish and Wildlife Service, Bureau of
Indian Affairs, Bureau of Reclamation, and the U.S. Geological Survey.
It is the second largest user with 252 assignments, as shown in Table
4-3, in the Washington, D.C. area. The location of the assignments is
shown in Figure 4-8. DOI primarily utilizes conventional simplex and
half duplex analog wideband systems for building security, executive
services, maintenance, and law enforcement. The DOI plans to convert all
LMR radios to digital narrow-band. They are also in the initial planning
stage, and are looking for partners, to establish and share a
Washington, D.C. area P25/TIA 102 compliant digital trunked system with
the U.S. Park Police.

![](media/image17.jpeg){width="4.388888888888889in"
height="2.7284722222222224in"}

[]{#__RefHeading___Toc71359239 .anchor}**Figure 4‑16. Plot of DOI
Frequency Assignments within a 100 Mile Radius**

**of Washington, D.C. in the 162-174 MHz Band**

### United States Department of Justice (DOJ)

The DOJ has a primary mission to "enforce the law and defend the
interests of the United States according to the law, to provide federal
leadership in preventing and controlling crime; to seek just punishment
for those guilty of unlawful behavior; to administer and enforce the
nation's immigration laws fairly and effectively; and to ensure fair and
impartial administration of justice for all Americans."[^32] Wireless
communications are critical to meet these mission requirements. DOJ uses
the 162-174 MHz band extensively for its LMR operations and it is the
largest user of this band with 672 assignments, as shown in Table 4-3,
in the Washington, D.C. area. The location of the assignments is shown
in Figure 4-9. DOJ currently utilizes a series of multi-channeled,
pseudo-simulcast (non-synchronized), wideband (25 kHz) analog repeaters
located throughout the Washington, D.C. area. The system is also
augmented with voting repeaters to "extend" the transmit range of the
portable radios. Many of the voted receivers are connected to the
network via landline.

The future plans for the DOJ involve the development of the IWN.[^33]
The IWN initiative will consolidate all of the DOJ bureaus into a single
LMR communications system. This new digital narrowband (12.5 kHz)
system, which utilizes both the 162-174 MHz and 406.1-420 MHz bands, is
being developed to increase spectrum efficiency, improve
interoperability among all bureaus within DOJ as well as other federal
law enforcement agencies, and maximize efficiencies and savings through
shared communications systems. The IWN will consolidate the
communications needs of the Office of the Attorney General, Federal
Bureau of Investigation (FBI), Drug Enforcement Administration (DEA),
Immigration and Naturalization Service (INS), U.S. Marshals Service
(USMS), Bureau of Prisons (BOP) and various bureaus of the DHS. Section
6 of this report has a complete description of the IWN initiative.

![](media/image18.jpeg){width="5.444444444444445in"
height="3.501388888888889in"}

[]{#__RefHeading___Toc71359240 .anchor}Figure 4‑17. Plot of DOJ
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band

### United States Department of the Treasury (Treasury)

The Treasury Department has a primary mission to promote prosperous and
stable American and world economies, manage the government's finances,
and safeguard our financial systems.[^34] Prior to March 2003 Treasury
also protected our nation's leaders and pursued a safe and drug-free
America.[^35] Wireless communications are critical to meet these mission
requirements. For example, the USSS provides protection for the
President, Vice President, and political leaders of the United States,
as well as protection to visiting foreign dignitaries. Treasury uses
both the 162-174 MHz and 406.1-420 MHz bands for 95 percent of its law
enforcement and protection operations. The majority (more than 80
percent) of their land mobile radio equipment operates in the 162-174
MHz band.[^36] Treasury is the third largest user with 231 assignments,
as shown in Table 4-3, in the Washington, D.C. area. The location of the
assignments is shown in Figure 4-10. Treasury currently uses a variety
of wideband analog systems based on the mission requirement. The USSS,
due to their mission requirements, relies mostly upon mobile and
hand-held radios, with repeaters, as necessary to extend the coverage of
their radios. Treasury also has major in-building coverage requirements,
such as bank vaults and building security, which requires them to use
in-building repeaters for "campus" type communications. Treasury's
future plans include joining the IWN to satisfy the majority of their
communications requirements.

![](media/image19.jpeg){width="5.433333333333334in"
height="3.3229166666666665in"}

[]{#__RefHeading___Toc71359241 .anchor}**Figure 4‑18. Plot of Treasury
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band**

### United States Capital Police (USCP)

The USCP is responsible for the safety and security of all members and
staff of the United States House of Representatives and the United
States Senate while they are physically located in and around the
buildings of the Capitol campus and other locations within Washington,
D.C. USCP also assists the United States Park Police, the United States
Secret Service, Amtrak Police, Washington Metropolitan Area
Transportation Agency (WMATA) Police, and the Washington, D.C.
Metropolitan Police as needed for motorcades, demonstrations, emergency
responses, and other special events.

In the Washington, D.C. area, the USCP has 25 assignments, as shown in
Table 4-3. Figure 4-11 shows the location of those assignments. The USCP
has ten frequency assignments in the VHF spectrum for use in the
Washington, D.C. metropolitan area. These are paired into five channels
used as a voting repeater system with satellite receivers and high power
base stations. The combination of over 100 satellite receivers and high
power transmitters provides officers and agents of the USCP with
coverage of the Capitol and all buildings in the Capitol campus as well
as off-campus communications in the Washington, D.C. metropolitan area.
The USCP also has one shared frequency pair assignment for use when
outside the Washington, D.C. metropolitan area.

The five "in-town" frequency pairs are used for voice communications 365
days per year. The single shared "out-of-town" assignment pair is used
when the members Congress have a scheduled offsite event that requires a
presence of officers and agents of the USCP for security and protection.
The USCP also provide on-site security for congressional retreats and
conferences at remote locations. While securing these locations, USCP
utilizes shared frequency assignments to coordinate their efforts.

The USCP intends to continue conventional analog voice operations on all
the existing assigned VHF frequencies to comply with the narrowband
requirements. Equipment that is narrowband compliant is currently being
purchased and issued to the officers and agents. The target date to
complete the conversion to narrowband is late November 2004.

The USCP is planning to implement a full simulcast site on their Channel
4 (wide area channel) and a multi-transmit (simulcast, not timed) site
on Channels 1, 2, 3, and 5 near Cheltenham, Maryland, where the new
Federal Law Enforcement Training Center (FLETC) is being built. The USCP
is planning to have a backup command center at the Cheltenham facility.
There are no plans at this time to convert to any form of digital,
shared agency, or trunked voice communications.

![](media/image20.jpeg){width="5.444444444444445in"
height="3.3229166666666665in"}

[]{#__RefHeading___Toc71359242 .anchor}**Figure 4‑19. Plot of USCP
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band**

### United States Postal Service (USPS)

The USPS is a national institution that is an integral part of the
infrastructure of the American economy. The USPS "binds the nation
together through the business, literary, and personal correspondence of
the people, providing prompt, reliable service to all communities as
required by the Postal Reorganization Act of 1970."[^37]

The USPS has 41 area specific assignments, as shown in Table 4-3, in the
Washington, D.C. area. Figure 4-12 shows the location of these
assignments. The USPS is divided into two major bureaus, the Mail and
U.S. Postal Inspection Service both of which use the LMR system in the
VHF band.

[Mail Bureau]{.underline}

Currently, the Mail Bureau utilizes LMR systems at mail processing
facilities within the Washington, D.C. area. These facilities have
extensive requirements for in-building communications. The
communications systems are used for maintenance, mail processing, safety
and emergency operations. The communications at these facilities
typically provide coverage around the facility for about 2-3 miles. The
configuration presently is analog with multiple repeaters and an
extensive in-building antenna system throughout the facilities. In some
facilities, there are outside communications between mobiles and the
repeater. The USPS is in the process of converting the wideband VHF
systems to narrowband.

The Mail Bureau anticipates that the present VHF assignments for
internal building communications will move to the UHF band. External
mobile communications, however, will most likely remain in the VHF band.
Both UHF and VHF equipment will remain analog.

[U.S. Postal Inspection Service]{.underline}

Presently, the U.S. Postal Inspection Service utilizes conventional
analog VHF LMR assignments for both in-building and external
communications between repeaters, bases, mobiles and handhelds. The U.S.
Postal Inspection Service is moving toward a UHF communications system.
The wideband VHF assignments will be eliminated in place of UHF
narrowband multi-link technology. There will be some VHF narrowband
assignments to be used for interoperability between the bureaus and
other law enforcement agencies.

![](media/image21.jpeg){width="5.444444444444445in"
height="3.3229166666666665in"}

[]{#__RefHeading___Toc71359243 .anchor}**Figure 4‑20. Plot of USPS
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band**

### United States Department of Veterans Affairs (VA)

The VA's mission is to provide integrated and innovative health care
services and benefits to eligible veterans and their beneficiaries.[^38]
The VA has 30 assignments, as shown in Table 4-3, in the Washington,
D.C. area. Figure 4-13 shows the location of these assignments. The VA
operates several conventional wideband systems in the area supporting
law enforcement, fire and security, emergency medical services, and
maintenance in and around their hospital grounds and headquarters. The
VA is in the process of moving its Washington, D.C., LMR operations out
of the VHF band and joining the 1CommWireless narrowband trunked system,
a commercial service operating in federal spectrum.[^39] The VA's
Baltimore operation has already transitioned to analog narrowband and is
expected to remain analog until the end of the equipment's life cycle.

![](media/image22.jpeg){width="5.444444444444445in"
height="3.3229166666666665in"}

[]{#__RefHeading___Toc71359244 .anchor}**Figure 4‑21. Plot of VA
Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band**

### Other Agencies or Bureaus

Agencies or bureaus within this group are comprised of various federal
government entities that have twenty or fewer assignments in the 162-174
MHz band within the Washington, D.C. area. Table 4-3 provides a list of
the other agencies or bureaus and breakdown of their assignments. Figure
4-14 provides the location of these assignments. The assignments used by
these entities are primarily used for law enforcement, building
security, administrative, maintenance, or paging. Most agencies utilize
simplex or half-duplex analog wideband networks, with some of the larger
networks (e.g., the Government Services Administration's in-building
maintenance network), utilizing base stations or repeaters to provide
the necessary in-building coverage for the numerous federally owned
buildings they are responsible for. Some agencies, such as the Social
Security Administration, are sharing frequencies and networks with other
agencies because they do not have large enough requirements to justify
their own systems. Most of the nets are agency-exclusive and the area of
coverage required is just their headquarters building or buildings
within a "campus" type environment. Future narrowbanding requirements
for many of these agencies will be accomplished by a simple one-for-one
swap-out of analog wideband to analog narrowband radios. Other agencies,
such as the State Department, have already migrated to conventional
narrowband digital radios.

![](media/image23.jpeg){width="5.444444444444445in"
height="3.3229166666666665in"}

[]{#__RefHeading___Toc71359245 .anchor}Figure 4‑22. Plot of Other Agency
or Bureau Frequency Assignments within a 100 Mile Radius\
of Washington, D.C. in the 162-174 MHz Band

## Summary

This section provides an overview of the federal agencies' uses of the
162-174 MHz band in the Washington, D.C. area. In the early 1990's, NTIA
mandated that the federal agencies migrate to more spectrally efficient
narrowband technologies in this band by January 1, 2005. Agencies are at
different stages of meeting the narrowband mandate (see Section 5). This
includes: already procured narrowband equipment to replace wideband
radios, narrowband equipment on order, new systems proceeding through
the test and evaluation phase, or having plans in development for
replacement systems. Some agencies stated that due to their unique
mission, sharing of systems may not be practical, while other agencies
stated that if the opportunity were presented to them, they would
consider joining a shared system (e.g., IWN).

#  OTHER FEDERAL GOVERNMENT EFFORTS

**REGARDING SPECTRUM EFFICIENCY**

##  General

Since there is limited land mobile spectrum, agencies must employ new
technologies and techniques to satisfy future requirements. The areas in
which the federal government is implementing new technologies and
techniques to improve spectrum efficiency include, but are not limited
to, the following: migration to narrowband technology, integrated
wireless networks, performance standards, and trunking technology. This
information is important to understand for potential incorporation into
the study. This section provides a brief discussion of some of the
various mandates, initiatives, and programs for improving spectrum
efficiency in the federal government.

##  Migration to Narrowband Technology

In 1992, Congress passed the Telecommunications Authorization Act of
1992.[^40] Title I of this act required NTIA to develop and implement a
plan to make federal LMR systems use more spectrum efficient
technologies. A report summarizing the plan and its implementation
schedule was prepared and submitted to Congress as required by the
legislation.[^41] As part of this plan, NTIA selected a 12.5 kHz channel
width for re‑channeling (or re‑farming) the federal fixed and mobile
bands.[^42] The reduction in channel width from 25 kHz to 12.5 kHz will
effectively double the number of available channels in the 162‑174 MHz
and 406.1‑420 MHz bands.[^43]

The federal public safety agencies' pursuit of more spectrum efficient
technologies is a necessary tool to satisfy the growing demands for
wireless communications within the federal government. As stated in the
previous section, the federal agencies are in various stages of meeting
the NTIA narrowband mandate.

##  Technical Performance Standards

NTIA has long been an advocate of technical standards for receivers to
minimize interference and increase overall spectrum efficiency. In
addition, state and local public safety entities are also recognizing
the importance of establishing receiver standards to minimize
interference. As the demand for wireless services continues to grow,
straining the limited spectrum resources that are available, it is
becoming increasingly important to manage the resource by considering
total system performance. Thus, both the transmitter and receiver
performance characteristics must be considered for maximum spectrum
efficiency. In the 162‑174 MHz and 406.1‑420 MHz bands, NTIA has adopted
receiver performance standards, in addition to transmitter performance
standards, that include: intermodulation rejection; adjacent channel
selectivity; and spurious response attenuation.[^44] NTIA and the
federal public safety agencies believe that receiver performance
standards are necessary to reduce interference from adjacent channel
transmitters. This will allow transmitters and receivers to operate
closer to each other, improve performance, and increase the overall
efficiency of these bands.

On March 24, 2002, the FCC released a Notice of Inquiry (NOI) that
requested information to a variety of questions pertaining to the use of
receiver standards.[^45] NTIA submitted reply comments to the FCC's NOI
encouraging the use of receiver standards, where appropriate, to prevent
interference and utilize the spectrum more efficiently.[^46]

The federal public safety agencies have also engaged in a long‑term
standards development process known as P25/TIA 102, a collective effort
by industry and the state and local public safety agencies. This
multi-phase effort has resulted in the development of an extensive set
of standards for digital public safety wireless communications.[^47]
Phase 1 of P25/TIA-102 specifies a 12.5 kHz channel width consistent
with the NTIA narrowband mandate. Phase 2 provides a migration path to a
narrower channel width of 6.25 kHz (or equivalent) as technology
permits. The technology readiness obstacles currently associated with
P25 Phase 2 include battery size and weight, linear amplifiers, and
oscillator stability. Also, based on information from manufacturers, the
6.25 kHz Phase 2 option is likely to be delayed several years due to
technical problems with encryption techniques in very narrow bandwidths.

### Trunking Technology

The use of trunking technology as a means of increasing the efficiency
and utility of spectrum resources is starting to be considered within
the 162‑174 MHz band and is already in use in the 406.1‑420 MHz band.
Federal agencies use trunked systems for limited areas with a high
concentration of use and for campus environments, such as federal
prisons, hospitals, laboratories, and training facilities. The DOD has
the largest number of trunked systems operating and planned within the
406.1‑420 MHz band. DOD uses these systems to satisfy the important
needs of national security, training, administration, and emergency
preparedness at its various facilities. Some planned federal systems,
such as the IWN and the DOD Enhanced Land Mobile Radio (ELMR) System,
will use trunking technology in their designs to satisfy some of their
requirements, especially in areas with large concentrations of users.

### 162-174 MHz Band Restructuring

Although specifications and standards have long existed for equipment
operating within the radio spectrum environment, the 162-174 MHz band is
currently unstructured in its accommodation of user applications.
Specifically, the current band allocation does not include separate
frequency sub-bands for base station transmitters and mobile
transmitters. Historically, this has not presented insurmountable
difficulties for user applications within the band because spectrum has
been readily available and most applications use simplex technologies.
However, as the band becomes more congested, the ability to obtain
additional suitable spectrum becomes increasingly difficult, even with
the implementation of improvements in equipment technology (e.g., 12.5
kHz channels). As more users move to repeaters, trunked systems, and
other technologies that require duplex frequencies, the need for a
structured band becomes more evident. Structuring a band that already
exhibits heavy use is a complicated process, and can also have numerous
implications for spectrum management, the users, and their associated
operations already within the band.

### Frequency Reuse

Although the amount of spectrum available is finite, any given portion
of spectrum can be re-used many times over, depending on the right
circumstances. In many cases, the "right circumstances" includes the
requirement that multiple users be separated by enough geographical
distance so that the signals from the various user radios do not
interfere with each other. If too large a distance is chosen, frequency
re-use efficiency will suffer and not as many users will be able to use
that frequency. If too small a distance is chosen, user systems will
interfere with each other.

For routine licensing in a common radio service (e.g., federal LMR
systems), theory and practical experience have often been summarized in
procedural "rules-of-thumb" that require different users, on the same
frequency, be separated by some fixed distance, e.g., 100 miles. For a
specific set of users, however, the required minimum separation distance
can vary over a wide range, depending especially on the propagation of
radio signals over the specific terrain that separates the specific
users. For a specific set of users and terrain, the rule-of-thumb
separation distance can be much too large, resulting in inefficient
frequency re-use. However, if the rule-of thumb distance is too small,
interference may result.

The frequency reuse issue can be investigated in several ways. First,
the existing procedure for establishing separation distances can be
compared to terrain-dependent propagation models, agency requirements,
and required signal to interference ratios for new systems. Once this is
accomplished, it can be determined if existing separation policies could
be refined to provide improved frequency re-use criteria. Secondly,
possible changes in spectrum management techniques could be examined to
determine whether the use of more accurate technical modeling used to
routinely evaluate the required separations for specific users, will
provide a useful amount of improved geographical frequency re-use. In
this case, "useful" means a balance between improved re-use and the
increased cost of processing a user assignment, as well as less future
flexibility to make use of an assignment.

In addition, it should be noted that frequency re-use can be enhanced by
deliberately restricting the size of transmitter coverage areas (e.g.,
low power/low antenna height sites). Such techniques also greatly
decrease the required minimum separation distance for re-using a
frequency. Although such small-cell techniques have been widely used by
cellular systems, they have not yet been widely used by public safety
agencies due to costs associated with constructing additional sites.
Nevertheless, public safety agencies may potentially benefit from the
use of small cells in a dense urban setting. The subject of frequency
reuse as it relates to spectrum efficiency will be addressed in
subsequent phases of this report.

## Initiatives And Spectrum Efficiency Improving Programs

### NTIA Spectrum Summit

NTIA held a Spectrum Summit in April 2002 to help identify the best
solutions to challenges posed by management of the nation\'s airwaves.
The purpose of the spectrum management and policy summit was to explore
new ideas to develop and implement spectrum policy and management
approaches that will make more efficient use of the spectrum; provide
spectrum for new technologies; and improve the effectiveness of domestic
and international spectrum management processes.[^48]

During the Spectrum Summit one of the major concerns expressed by the
federal and private sector spectrum management community, and radio
service users and providers, was future spectrum availability to satisfy
needs to expand services and to accommodate new technologies. It was
suggested that additional spectrum to fulfill these needs could possibly
come from current users improving their spectrum efficiency through new
technologies or creative assignment approaches, increased sharing, more
realistic interference protection criteria, or some combination of all
of these.

### Federal Communication Commission's (FCC) Spectrum Policy Task Force

In June of 2002, the FCC convened the Spectrum Policy Task Force to
address a number of policy issues important to improving the way
spectrum is managed. One primary issue addressed by the task force was
spectrum efficiency. Spectrum efficiency questions focused on how to
promote and measure spectrum efficiency, while protecting the ability of
public safety entities to do their jobs in light of the increasing
demand for spectrum. In its attempt to develop a method to measure
spectrum efficiency, the task force conclude[^49] that, due to
differences in radio services, it was not feasible to select an
objective means to compare unlike services and users.[^50] The Task
Force identified three variations on and definitions for the term
"efficiency" as applicable to spectrum management: spectrum efficiency,
technical efficiency and economic efficiency.[^51]

Both NTIA's Spectrum Summit and the FCC's Spectrum Policy Task Force
provided valuable insight into current thoughts on spectrum efficiency.
One of the common themes expressed in both forums is improving spectrum
efficiency, especially in the bands used for mobile communications. Many
have observed that the federal government agencies have fewer mobile
users per unit of the spectrum than is true for business, non-federal
public safety, or commercial (cellular phone and PCS) applications.
Public safety users require high reliability and availability with
frequency channels whose traffic loads change drastically with planned
or unplanned events. As a result of these operational requirements,
federal public safety frequencies are not in use all of the time, which
could be perceived as inefficient use of the spectrum. Additionally,
federal users generally require frequencies on a nationwide basis,
limiting the ability to re-use much of what is used.

### General Accounting Office (GAO) Reports

The GAO, in its report on improving spectrum managemen[^52], found that,
although NTIA has oversight activities that encourage efficient use of
the spectrum, the lack of resources has hindered the agency's
effectiveness.[^53] Lack of resources was also an issue for the federal
agencies. In fact, the federal agencies reported difficulties
implementing NTIA initiatives such as land mobile narrowbanding,
primarily due to staffing, priority, and budget issues. The report also
points out that many federal government uses of the spectrum do not have
commercial counterparts and cannot easily be compared using common
efficiency measures, such as the number of subscribers per hertz.[^54]
The report also briefly explored the concept of using spectrum fees as
an incentive for spectrum efficiency. Interestingly, at least one of the
agencies interviewed stated that NTIA's current reimbursement structure
for spectrum management services was not large enough to encourage
spectrum efficiency. Spectrum fees to encourage efficiency versus fees
to recover the cost of spectrum management will be addressed in a
follow-on study.

In another repor[^55] on current issues relating to spectrum management,
the GAO, through interviews with agency and industry officials,
attempted to determine how the federal government encourages efficient
use of spectrum by federal agencies.[^56] In findings similar to the
previous report, the GAO concludes that NTIA is required by law to
promote the efficient and cost-effective use of the spectrum it manages.
The process by which NTIA certifies and authorizes (assigns) spectrum is
designed to promote efficiency, but the justification for use of
spectrum and review of current assignments is largely left up to the
individual agency. The GAO found that inadequate resources were the
primary reason for a lack of comprehensive review of assignments,
preventing any enforcement or monitoring activities to identify and
return unused spectrum. GAO found that, in many cases, the five-year
review process, the primary tool that NTIA uses to determine if assigned
spectrum is actually used, is either not accomplished or overdue.[^57]

### Presidential Initiative to Develop, Implement Spectrum Policy for the Twenty-First Century

On June 5, 2003, President Bush announced a new initiative to develop a
radio spectrum policy for the Twenty-First Century.[^58] The Executive
Memorandum directs the DOC to facilitate policy changes to create
incentives for more efficient and beneficial use of spectrum and to
provide a higher degree of predictability and certainty in the spectrum
management process as it applies to incumbent users; and develop policy
tools to streamline the deployment of new and expanded services and
technologies, while preserving national security, homeland security, and
public safety, and encouraging scientific research.[^59] The Secretary
of Commerce announced the formation of a high-level interagency task
force under the Executive Memorandum issued by the President that will
recommend ways to stimulate more efficient use of the radio frequency
spectrum by federal government users. The task force will provide
recommendations that promote effective, efficient and beneficial use of
spectrum without unacceptable interference to critical incumbents.

As a part of the initiative, NTIA published a NOI seeking comments on
policy reforms relative to the management of the radio frequency
spectrum.[^60] The NOI contains a list of questions to assist in
identifying issues that may need to be addressed in changing U.S.
spectrum management policies. Comments to the NOI were due May 2004.

The recommendations resulting from these activities were included in a
two-part series of reports released by the Secretary of Commerce in June
2004, under the title *Spectrum Policy for the 21st Century- The
Presidents Spectrum Policy Initiative*.[^61] These reports contain
recommendations regarding the efficient use of the radio spectrum.

### SAFECOM Program Office

SAFECOM was established in the spring of 2002 to address the wireless
communication needs of public safety organizations. SAFECOM serves as
the umbrella program within the federal government to help local,
tribal, state and federal public safety agencies improve public safety
response through more effective and efficient interoperable wireless
communications. As a public safety practitioner driven program, SAFECOM
is working with existing federal communications initiatives and key
public safety stakeholders to address the need to develop better
technologies and processes for the cross-jurisdictional and
cross-disciplinary coordination of existing and future communications
systems.

### 1CommWireless (Formerly FEDSMR)

The Washington/Baltimore system, operating under the name of
1CommWireless, is one of several federal communications systems in the
northeast and southeast that is owned and operated by a commercial
vendor that provides service to federal users. The Washington/Baltimore
system is currently transitioning to a new narrowband, multi-site system
using the transcript protocol (this protocol provides a digital backbone
supporting system enhancements such as seamless roaming, over-the-air
re-keying (OTAR), console interfaces, privacy, and compatibility with
other systems). Radio equipment for use on the system is available from
several vendors at a price considerably less than the wideband radios
formerly employed on the company's previous analog system. The sites
include Baltimore Washington International airport, Martinsburg, West
Virginia, Veterans Administration Building at Lafayette Park, Crystal
City, and Dulles Airport with several others currently under
consideration. The system will be using twenty channel pairs that will
be reused throughout the area similar to cellular radio's reuse of the
spectrum. The frequencies are assigned to NTIA, which permits the
contractor, in this case, 1CommWireless to use the frequencies to
provide telecommunication services exclusively to the federal government
in the 406-420 MHz government band. This system supports over 2,000
subscriber units. Current federal government agencies using the
1CommWireless system include Bolling Air Force Base, Smithsonian
Institution, United States Holocaust Memorial Museum, United States
Senate, Office of the Inspector General, and the Naval District of
Washington Transportation among others. These user organizations pay a
monthly fee based on the number of subscriber units accessing the
system. Depending on the number of talk group assignments, monthly fees
may be as low as \$24.00 a month.

Federal agency participation in the 1CommWireless system is relatively
small compared to the overall federal government radio equipment usage
in the Washington/Baltimore area. This is because there are large
government owned and operated systems in the area that were in operation
before the 1CommWireless system became operational in 1990.

### Integrated Wireless Network (IWN)

The U.S. House of Representatives, Committee on Appropriations Report
addressed the issue concerning narrowbanding of the current DOJ land
mobile systems. Specifically, it was noted that any DOJ narrowband
conversion initiative must be based upon a comprehensive strategy, which
achieves as one of its goals "maximized efficiencies and savings through
shared infrastructure and common procurement strategies."[^62] To
increase spectrum efficiency and maximize the limited spectrum resources
available to federal public safety agencies, DOJ, DHS, and Treasury are
developing the IWN to address the needs of the numerous bureaus and
agencies within their departments. The IWN will provide national
coverage through hybrid LMR systems, which will consist of both trunked
and conventional digital narrowband equipment.

Overall spectrum planning and support activities critically influence
the IWN network design through four distinct phases.

1.  Phase 1 -- Existing Capabilities Survey. In this phase, existing
    users within the scope of the IWN project design area are identified
    and defined by Operations and Engineering, and then characterized in
    accordance with their legacy system operational capabilities,
    coverage, and requirements.

2.  Phase 2 -- Operational Requirements Definition. In this phase, user
    requirements anticipated to be supported by the IWN network are
    specifically defined by Operations. This phase is critical in
    determining the overall spectrum resources necessary for support of
    IWN network operations.

3.  Phase 3 -- Frequency Selection and Assignment Processing. The third
    phase involves detailed identification and formal
    coordination/processing of the specific frequency assignments
    required for site operations within the IWN.

4.  Phase 4 -- Operational Transition/Implementation. The final phase of
    spectrum planning and transition activities within the IWN is
    heavily predicated on the availability of the selected frequency
    resource to support the network's overall operation channeling
    requirements.

Once the planning phases are concluded, an initial pilot test project
will be conducted in the State of Washington. The IWN will be based on
digital technical standards that maximize the use of the available
spectrum and will be P25/TIA 102 compliant. The IWN is planned to
increase spectrum efficiency through shared infrastructure and utilizing
digital narrowband technology. The system will also provide economies of
scale through common procurement strategies.

With limited spectrum resources in the 162‑174 MHz and 406.1‑420 MHz
bands, more federal public safety agencies are looking at IWN-type
systems to maximize the use of spectrum resources to meet the increasing
spectrum demands of their agencies.

### United States Department of Defense Trunked Network

The Department of the Army is planning to implement a P25/TIA-102
compliant, voice over internet protocol (VoIP) capable, digital
narrowband trunked system in the 380-400 MHz band. The Regional Concept
2005+ plan is to expand the system region-by-region to eventually
connect military installations throughout the United States. Most of the
current operations using the 162-174 and 406-420 MHz bands will relocate
to this new system. The system will be built-out in two phases. The
first phase build-out will include Army installations within the
National Capital Region (NCR) and the Military District of Washington
(District of Columbia, Virginia, Maryland, and New York), along with a
Navy system at the Navy Annex, Quantico Marine Base, Quantico, Virginia.
The second phase build-out will include Navy and Air Force installations
within the NCR. Dispatcher requirements will be controlled by digital
consoles, or via mobile or base station assigned to each team or agency
at the installation. The trunked system will be controlled from a
central location by means of a Communications System Director, to
facilitate collection of usage data, dynamic system configuration and
reconfiguration, and control. Connectivity to the alternate zone and
system controller main repeater site will be via T1, fiber, and hardwire
over existing infrastructure, or constructed RF line-of-sight systems.
Users will be comprised of DOD Operations, Defense Protective Service,
fire departments, law enforcement center, medical, force protection,
information management, administrative, public works, and Emergency
Operations Center, training, and post support. The system is planned to
employ cross band capabilities to allow interoperability with the
multitude of federal, state, and local agencies in the area.

**Page 5-10/Blank**

#  THE SIGNAL CAPACITY ANALYSIS PROGRAM (SCAP)

## General

One of the first steps in designing future spectrum efficient radio
networks for federal radio systems in the Washington, D.C. area is to
understand how much service is needed, of which types, and in what
locations. The SCAP is designed to process existing GMF data to provide
this radio service information. Every federal agency using the radio
spectrum must have frequency assignments (licenses) listed in the GMF
for every transmitter in use. Therefore, the GMF should contain
frequency records corresponding to all federal radio systems in use in
the Washington, D.C. area. Moreover, these GMF records will usually
contain sufficiently detailed technical information that the records can
be analyzed to accurately estimate the coverage area of the selected
assignments. For this Phase 1 study, the GMF data were analyzed for all
assignments located within a 100-mile radius of Washington, D.C. for
frequencies within the 162-174 MHz federal land mobile band and
supplemented with agency inputs.

## Definition of Signal Capacity

There are several ways to define the amount of "service" provided by a
given radio system. These definitions need to reflect the type of
service provided by the particular radio systems, e.g., a radar system
would be defined by completely different factors than a mobile radio.
Different service definitions would be assumed to provide different
types of information, would present various difficulties in obtaining
the required information, and would have different applicability to the
problem of providing specifications for a future radio system. The
definition of radio service selected for this work is called signal
capacity (SC). The SC is defined as the number of independent 2-way
voice radio channels that can be received by a mobile radio user at a
given geographical location. Note that the definition includes the word
"received" rather than a phrase like "used by." The SCAP considers only
base station transmitters and the geographical distribution of the field
strength that they produce. This model is based only on the
base-to-mobile signals that can be received by mobile users. The SC
model includes no information about base station receivers, or any
receivers whatever. However, any future radio system designed to meet
the SC specifications produced by the SCAP would also need to meet
suitable base station receiver functions (possibly including
receive-only sites) and (probably) be capable of mobile-to-mobile
operation.

This SC definition is particularly useful for several reasons:

1.  The major service provided to federal users in the 162-174 MHz band
    is two-way voice channels to mobile users. Therefore, this
    definition captures most of the use in the 162-174 MHz band.

2.  The SC is additive. This means that the SC produced by Agency X
    assignments can be added to the SC associated with Agency Y
    assignments to obtain a SC for both agencies.

3.  The SC can be calculated from data that is available in GMF license
    records and technical models, including transmitter data,
    terrain/ground cover data, and propagation models.

4.  The SC could be used to design alternative future radio systems,
    which would provide coverage to various geographical areas, using a
    sufficient number of transmitter channels to match or exceed the
    respective SC values.

However, the SC definition makes many simplifications that may limit its
usefulness in specific circumstances. These include:

1.  There is no data on whether a given channel is lightly or heavily
    used. However, the existence of a radio channel used or not used
    suggests that the system was built for a reason, and that reason
    still must be presumed to exist when a future system is built to
    replace the existing radio system.

2.  All voice channels are considered identical, whether analog or
    digital, narrowband or wideband, simplex or duplex, high priority or
    low, etc. Equally important, SC only considers the radio link, with
    no distinction as to what capabilities are available via that link:
    data, encryption, database access, telephone access, wide area
    access, etc. For the purpose of SC, "a channel is a channel is a
    channel."

3.  Only permanently sited transmitters (and their corresponding
    coverage areas) are considered here; all receiver assignments and
    mobile transmitters are ignored. Future studies on designing
    replacement systems will also need to duplicate receiver coverage
    specifications (e.g., receive-only sites etc.). It is assumed mobile
    transmitters would probably not be replaced by a new permanent
    infrastructure. Therefore they do not need to be included.

4.  Many assignments include multiple station classes, different
    emission designators, and different transmitter powers. The SCAP
    analyzes the highest power signal from these multiple sets of
    specifications, giving the largest possible coverage area. In some
    cases, the assignments may authorize the use of transmitter power
    higher than the actual transmitter power installed.

5.  A single coverage criterion is used with SCAP, although various
    agencies may require a variety of coverage definitions. For example,
    some agencies may require high-reliability, in-building access to
    portable receivers, while other agencies may accept less reliable

> rural access via outdoor vehicular radios. A single criterion of 10
> microvolts/meter (µV/m) with 50 percent confidence and 90 percent
> reliability was selected to define coverage.[^63]

In summary, although the SC may not provide an exact measure of the
service that a radio system (or a set of radio systems) produces, it
provides a fairly realistic measure of service in the 162-174 MHz band
that can be calculated. The SC is a particularly useful measure, because
radio systems can be relatively easily designed to match or exceed a
given SC, with a reasonable assurance that a new full-featured radio
system (e.g., a trunked system) would reliably match or exceed most
realistic performance measures of the current system.

## Basic SCAP Analysis

The SCAP performs its analysis in several stages. Additional details are
available in Appendix A. The first stage includes reading a modified
version of the GMF, which has been sorted to include assignments in the
162-174 MHz band within a 100-mile radius of Washington D.C. In
addition, each assignment record has been augmented with a function code
that tells SCAP how each assignment record is to be analyzed. The
function code includes a determination of function and network
identification. Since the analysis for each network is performed
independently, SCAP must first identify all transmitters belonging to
each network. A network is defined as any related set of transmitters
that are part of an integrated system or network following a uniform set
of SC rules. In general, a minimal network includes a single
transmitter. Other networks can include a simulcast system with 15 sites
and ten frequencies at each site.

The SCAP uses the GMF assignment data for each transmitter assignment to
obtain antenna and transmitter data, which is used with a terrain-based
propagation program to compute predicted field strengths from that
transmitter. The field strength predictions are combined with receiver
sensitivity data to predict a coverage area for each transmitter; all
field strengths higher than a certain threshold are assumed to provide
coverage (service) for mobile users. The predicted coverage is
calculated at one-mile intervals to show coverage over a 200-mile
square, centered on Washington, D.C.

The SCAP uses the basic coverage information to calculate a pair of peak
and average SC maps for each network, following the specific algorithms
for each function code, as described in Appendix A. The peak SC and
average SC maps for each network can be combined to give similar paired
peak and average SC maps for multiple networks by simply adding the
corresponding elements representing peak or average SC at respective
geographical locations. The peak and average SC maps can continue to be
added together to obtain peak and average SC maps for various larger
groups of networks. Continuing the process of addition, coverage maps
for groups of networks for individual agencies can become coverage maps
for whole departments, and ultimately, the entire federal government.

The SC maps are calculated at one-mile intervals for all locations over
a 200-mile square area. However, the GMF database used for these
calculations included only GMF records for systems located within a
100-mile radius circle, centered on Washington, D.C. Therefore, there
can be some substantial "edge" affects in this modeling. For example, a
transmitter located just outside the 100-mile radius circle would not be
included in the model at all, even though it could have a substantial
portion of its coverage area inside the area of the map. Furthermore, a
transmitter just inside the circle would be included in the model, but
part of its coverage area could lie outside the calculated area of the
square map. This reduction in the apparent size of its coverage area
could affect the numbers in the average SC maps.

The use of a 200-mile square represents a compromise between performing
the study using a larger square, which would require more extensive
analysis, and using a smaller square, which would cause the edge effects
to be relatively greater. A 200-mile square will produce minimal
distortions in the immediate Washington, D.C. area, though the
distortions could be larger near the edges of the map.

### Peak and Average Signal Capacity Maps

![](media/image24.png){width="4.95in" height="4.48125in"}Although the SC
was defined initially at a given location, it is convenient to summarize
the SC at many adjacent locations as a contour map, using colors or
contour lines to identify areas that have certain ranges of SC values.
Figure 6-1 shows examples of four maps from single transmitters sited at
Alexandria, Greenbelt, Hazlettville, and Preston. Each map shows
geographical areas of coverage from each transmitter. The quantity
plotted in these maps is called a "peak" signal capacity (PSC) map to
distinguish it from an "average" signal capacity (ASC) map described
later. The maps produced in this study are generated by calculating
predicted field strength at one-mile intervals over a 200-mile square
centered around Washington, D.C. The calculation uses transmitter and
antenna data obtained from the respective GMF files. The terrain-based
Longley-Rice propagation model is used in the analysis, with "coverage"
defined as all locations with field strength in excess of 10 µV/m. The
shaded areas of the maps indicate coverage from the associated
transmitter. Since only one transmitter is present in each of these
examples, every point on the maps will have coverage from either one or
zero transmitters, (i.e., SC values of either zero or one, representing
no coverage, or coverage by one transmitter). The effect of terrain is
visible in enhancing or shadowing the coverage areas. The PSC map can be
understood as showing the maximum number of independent users that could
be simultaneously served at any given location, assuming that no other
users were being served at other locations.

![](media/image25.png){width="5.059722222222222in"
height="4.570833333333334in"}An ASC map, as shown in Figure 6-2, can
also be created. The ASC map shows the maximum number of independent
users per square mile that can be served at one time if users were
distributed evenly across the coverage area of a transmitter. The ASC
map for an individual transmitter is determined by calculating the PSC
map, totaling the number of square miles of coverage for that
transmitter, and dividing the PSC values by the total coverage area.

This computation means that the ASC map values at each location will be
expressed in terms of users per square mile that the transmitter could
provide service to, assuming that users were evenly spaced across all of
the transmitter coverage area. Integrating the ASC values across the
entire coverage area of one transmitter will give a total of exactly
"one user." Figure 6-2 shows an ASC map of the same transmitter whose
PSC map was shown in Figure 6-1. Specifically, Hazlettville, in Figure
6-1, shows radio coverage of about 2,500 square miles (out of a total of
40,000 square miles included in the map). Therefore, the ASC map shows
that this transmitter would provide coverage to about .0004 users per
square mile, if the users were evenly distributed over the whole 2,500
square mile area of coverage, (2,500 mile squared x .00014 users/mile
squared = 1 user). As a convenience in reading the ASC maps, the actual
ASC values in this report have been multiplied by 10,000 before they
have been plotted, so that .0004 is plotted as "4". This gives values
that are easier to read and relate to PSC values. Note that a smaller
transmitter coverage area gives larger ASC values on the map. The
Preston transmitter in Figure 6-2 has a noticeably larger coverage area,
but the lighter shade corresponds to a plotted ASC value of around "2",
a number only about half as large as the ASC values corresponding to the
other three transmitters.

Both the previous ASC and PSC map examples describe use by one
independent user. This does not imply that only one individual user can
actually be served by the system at a given time. The independent user
may be a talk group with a hundred members that are simultaneously
receiving a common message. More likely, the one independent user would
be several talk groups, each with multiple users, who time-share the
single radio channel among themselves. The only constraint among the
multiple users in each of the multiple talk groups is that only a single
message can be carried by the radio channel at one time. Likewise, the
one independent user could actually be a single user.

The PSC map and the ASC map provide two different methods of looking at
the problem of providing service, based on different assumptions about
how users are distributed geographically. The PSC map assumes that all
users may be concentrated at the same geographic location. The ASC map
assumes that users are evenly distributed across the coverage area of
their respective base station transmitters. In analyzing the SC that is
provided by an existing transmitter, it is not known whether that
transmitter was intended to serve users who are statistically evenly
distributed across the coverage area or users that are usually located
in one small portion of the coverage area. Lacking this specific
information for each transmitter, the analysis covered the extreme cases
by calculating both the PSC and ASC maps. In many ways, the PSC and ASC
maps represent the worst and best cases of user geographical
distributions, respectively. Real-world user distributions presumably
must lie somewhere between these two extremes, but it is not necessarily
clear exactly where. Nevertheless, the PSC and ASC maps place bounds on
the effects of user location.

If all transmitters had the same coverage area, the PSC and ASC maps
would look identical, except for a scaling factor related to the
coverage area of the transmitters. However, if transmitters with one
coverage area are replaced with future transmitters having a different
coverage area, the assumptions about whether replacement transmitter
requirements scale proportionally to coverage area or not become very
important, since these two different assumptions give much different
results. ASC values scale proportional to coverage area; designing a new
system with micro cells having ten percent of the coverage area of
current transmitters would result in designing the micro cells to handle
ten percent of the traffic. PSC values do not scale with coverage area.
A ten percent-sized micro cell would still need to handle all of the
traffic of the standard transmitter, since it is possible that all of
the users from the standard cell may sometime be crowded into that
single micro-cell. Therefore, both sets of maps are important as a more
complete basis for designing a range of possible alternative radio
systems to match the current capabilities of users in the 162-174 MHz
band.

Although PSC and ASC maps show the coverage of individual transmitters,
they are particularly useful because individual SC maps for individual
transmitters can be combined with SC maps of other transmitters to get
SC maps corresponding to groups of transmitters. In particular, the PSC
map values at a given geographic location from one transmitter can be
added to the PSC map values at the corresponding geographic locations
for another transmitter to produce a PSC map for the combination of the
two transmitters. Similarly, the ASC map values for one transmitter can
be added to corresponding ASC map values for another transmitter, on a
point-by point basis to obtain an ASC map for the two transmitters.

In similar fashion, PSC maps for a few transmitters can be added
together to give PSC maps for arbitrarily large numbers of transmitters.
Thus, PSC maps can be obtained for specific commands, whole agencies, or
whole departments, or even the entire set of users in the Washington,
D.C. area. Similarly, the individual ASC maps can be combined to give
ASC maps for arbitrarily large groupings of transmitters.

### The Use of Function Codes to Define Signal Capacity of Networks

Although the previous descriptions of ASC and PSC maps have discussed
single transmitters, the lowest level of radio system that can actually
be analyzed to produce PSC or ASC maps is not a single transmitter but
is instead a "network." A network is a group of transmitters (one or
more) designed to produce a specific type of service over a given area.
In many cases, a network contains only a single transmitter. The concept
of network must be used to compute SC because, in many systems, the use
of one transmitter constrains how other transmitters can be used. For
example, if one simulcast transmitter is transmitting a signal, no other
simulcast transmitter on that channel can be simultaneously used to
transmit a different signal. Thus, the ability to receive an independent
signal at one location is dependent on what is happening at another
location. The network, as defined here, is the smallest set of
transmitters that must be included in the SC calculations to obtain an
accurate value. Once the ASC and PSC maps for a network have been
properly calculated, these values are independent quantities and SC maps
from one network can be freely combined with SC maps for other networks.

The SCAP uses the GMF frequency database as a source of technical
information about LMR transmitters in the 162-174 MHz band. A function
code (F, N) is added to each GMF assignment record that provides
additional information needed by the SCAP. The parameter F shows SCAP
what type of technology the network uses (i.e., what set of algorithms
to use to compute SC maps). Different algorithms are needed for
independent base stations, repeaters and multi-site repeater systems,
simulcast systems, trunked base stations and multi-site systems, and
others, as described in Appendix A. The parameter N shows what other
transmitters to include in this analysis. All transmitters with the same
N identifier belong to the same network. Transmitters are often assigned
as individual equipments, but the SCAP needs to perform calculations on
groups of transmitters (networks) therefore the "network" function codes
are used to enable this required grouping. A more detailed description
of the specific types of networks and the associated SC algorithms are
given in Appendix A.

![](media/image26.png){width="3.4895833333333335in"
height="3.03125in"}The function codes were determined by a study of the
GMF records and consultations with frequency management staff at the
various federal agencies. The function code determinations are only for
purposes of SCAP analysis and no actual changes were made to any GMF
records. Some GMF records did not fit exactly into the functional
categories that were established. Consultations were made with agency
staffs to attempt to get the closest possible fit.

![](media/image27.png){width="3.4895833333333335in"
height="3.15625in"}Figures 6-3 and 6-4 provide an example of the SCAP
analysis of a basic network, showing how different types of networks
give different PSC and ASC map results, in a network that consists of a
group of four base stations. These four transmitters will be analyzed as
a simulcast network and as a network of single-channel trunked radio
systems.

The PSC map for the simulcast system is shown in Figure 6-3 and the PSC
map for the trunked radio system is shown in Figure 6-4. The simulcast
system PSC map was created by first calculating the coverage areas of
each base station and placing a "1" at each location where coverage was
available from any of the four base station transmitters. In locations
where coverage is available from more than one base station, the PSC for
the simulcast system is still "1," since all base stations transmit an
identical message, so only one independent message can be received at
any location. This PSC simulcast system map functions as though the
radio system were a single transmitter with a very large coverage area,
with a single color shade and a PSC value of "1" at all locations that
get coverage from one or more transmitters.

Figure 6-4 shows the PSC map for the same four sites analyzed as trunked
sites. A four-site trunked radio system using independent frequencies to
provide coverage from each transmitter site could provide independent
messages from each site. Therefore, in all locations where coverage is
available from multiple base stations, the PSC values add together to
equal the number of different sites from which coverage is available. As
shown in Figure 6-4, some locations get independent coverage from as
many as three of the transmitter sites. The darker shading represents
the larger PSC values.

![](media/image28.png){width="3.5in" height="3.158333333333333in"}

The average SC value is determined by dividing the PSC at a specific
location by the area over which each transmitter provides coverage. In
the case of a simulcast system, the entire four-site simulcast coverage
area resembles what the coverage area of a single transmitter that
covers a very large area would look like. Therefore, the simulcast
system ASC map, Figure 6-5, looks identical to the simulcast PSC map,
except for a scaling factor that shows a single relatively low average
number of independent users per square mile that can be served by the
simulcast system.

![](media/image29.png){width="3.5in"
height="3.1645833333333333in"}Figure 6-6 shows the ASC map for the four
sites analyzed as trunked sites. The ASC values for the four base
station trunked network is calculated by finding the ASC values for each
base station on an individual basis, and adding the individually
calculated ASC values at points where coverage is available from
multiple stations. In this case, the transmitters operate independently,
so the coverage area is the respective area for each separate
transmitter. Since each transmitter can serve a different population of
independent users, the ASC values add together where coverage is
available from multiple transmitters.

Therefore, PSC and ASC are different for the four-site simulcast network
and the four-site trunked network. The peak usage per simulcast channel
would be one independent user per channel over the entire four-site
area. The peak use per trunked channel would be one independent user per
channel at many points, but there would also be locations that may
provide service to two to three independent users, due to overlapping
coverage areas from multiple sites.

The average number of independent users per square mile that the
four-station simulcast system can support would be smaller than the
number of independent users per square mile for the four-site trunked
system for two reasons. First, there is only one independent signal
available from the simulcast system, whereas the trunked system provides
multiple signals in many locations. Second, the coverage area is larger
for the simulcast system than for any of the individual trunked sites,
so the ASC value for the simulcast system is smaller than the ASC value
for any of the individual trunked transmitters. Therefore, the ASC
values, the average number of independent users per square mile, are
smaller for the simulcast system, at any given location, than for the
corresponding location on the ASC trunked system map.

The above analysis shows numbers that are based on independent users. An
independent user can be a single user or a large talk group with
hundreds of users as long as the talk group members all receive the same
messages. Many public safety systems are not designed to support
individual independent users, but are designed for talk groups
containing many users spread across a wide area. Under these
circumstances, large coverage areas are more important than being able
to locally serve multiple independent users. Therefore, the apparent
disadvantages of the simulcast system versus the trunked system may not
be as great as shown in these numerical examples, when large talk groups
spread across large areas are considered.

#  FEDERAL AGENCY SIGNAL CAPACITY MAPS

##  General

This section contains the SC maps for various agencies and groups of
agencies, resulting from a SC analysis of the Washington, D.C. area GMF
data within the 162-174 MHz band. The basic concepts of PSC and ASC have
been described in Section 6, with additional technical details included
in Appendix A. Also described in that section, and in Appendix A, are
the function and network codes used to convert GMF assignment files into
SC coverage maps

##  Technical parameters for Signal Capacity Maps

The SC maps contained in this section were generated from data found in
the November, 2002 GMF files. The SC maps were developed from all
assignments that are located within a 100-mile radius centered on
coordinates 38°54\'34\"N, 077°00\'00\"W, which corresponds approximately
to the National Capitol building. Assignments located outside of the
described 100-mile radius circle were not included in the analysis,
although the coverage areas of any included assignments were calculated
over a square that is 200 miles on each side. This means that there are
"corners" of the square that are outside the 100-mile radius circle
where coverage from transmitter assignments located inside the circle
were analyzed, but no GMF assignments in those corner areas were
included in the SC modeling. No assignments located outside of the
100-mile circle were included in the analysis, but transmitters would
normally be found outside this circle and provide additional coverage to
locations inside the circle. Therefore, there are expected to be "edge
effects" near the outside of the circle where less-than-expected numbers
of transmitters will be seen in the maps. The selection of a 100-mile
circle was intended to result in a minimum level of edge distortion over
most of the map, but especially in areas near Washington, D.C.

The geographically selected GMF assignments were categorized using the
function codes and network codes, according to how the respective
assignment should be analyzed by the SCAP. Transmitters selected for
inclusion in the SC modeling were analyzed to show their coverage areas.
For this analysis, the terrain-based Longley-Rice propagation program
was used, along with transmitter power, antenna, and location data from
the GMF. The coverage analysis assumed that any location should be
considered to have coverage if the 50-90 signal amplitude exceeded ten
microvolts/m. This coverage criterion was chosen as a compromise between
urban and rural coverage objectives, for a wide range of modulations and
bandwidths. Appendix A provides a more detailed description of the
model.

Many GMF assignments incorporate multiple modulations, bandwidths, and
transmitter powers. In this case, the highest transmitter power was used
to calculate the coverage area, ignoring other differences based on
modulation and bandwidth.

##  Interpreting the Signal Capacity Maps

The SC maps are designed to easily summarize the service that is
provided by existing federal mobile radio systems in the 162-174 MHz
band in the Washington, D.C. area. As described in Section 6 and in
Appendix A, two different types of SC maps were needed to describe
different aspects of SC. PSC maps show how many independent radio
signals are available at any given location to a radio receiver at that
location. Figure 7-1 shows an example of a PSC map for several selected
federal radio systems.

![](media/image30.png){width="5.25in" height="4.7972222222222225in"}

Figure 7-1 shows PSC values for all locations in a 200-mile square,
centered around Washington, D.C. These values were calculated for
locations spaced on a 1-mile grid. The color of the shading at every
location indicates how many radio signals can receive at that location.
Concentrations of radio signal coverage are located in the areas around
Washington, D.C. In addition to certain cities, the map shows county and
state boundaries, as well as major rivers and coastlines.

The red shades on the map show that a mobile user in several high-signal
areas can receive as many as 35 independent signals from various
transmitters analyzed on this map. However, at many locations outside
the high-signal areas, the white area shows that no signals would be
available to a mobile user. At various in-between areas, a few (but not
many) signals could be received by a mobile user. However, one
"independent signal" does not mean that only one user at one location
can receive the signal. Instead, a very large number of mobile users can
be simultaneously listening to that one same signal at many locations
across the map.

In addition, the SC map does not show whether the "one signal" available
at one location on the map is the same "one signal" that may be
available at other locations on the map. In general, this ambiguity does
not become troubling unless the required coverage is supplied by base
stations placed at considerably different locations than the original
base stations that were analyzed to produce the SC maps. Even assuming
that different base station locations were used, one would generally
expect that these SC map values would add up in different ways, some
better, and some worse that would not result in systematic difference
that would produce distorted results. However, consider the case where a
specific existing base station was sited to provide coverage to a
specific set of users operating in certain specific geographic areas.
Changing base station locations in a potential future system might
result in multiple base stations being required to provide coverage to
all of the users who were covered before by a single base station. This
could result in more future base stations being required than would
normally be calculated. The magnitude of this effect is not known.

Areas are considered "high-signal" because of the number of independent
signals present, not because the signals are strong signals (i.e., high
field strength). In fact, a small, high-signal, almost-vertical line
west of Washington is probably the result of a number of relatively
weak, but above the coverage threshold value, signals from Washington
adding to a number of the similarly weak signals coming from the
Hagerstown/Fort Royal area. Thus, the vertical line shown in Figure 7-1
is composed of a large number of weak signals.

The effects of terrain are clearly seen in the maps. For example, near
the lower, left-hand corner of the map is a diagonal line of
higher-signal locations. This is caused by locations in high mountains
receiving usable levels of signal from many distant radio base stations.
Similar effects are seen from many mountain ranges scattered over the
land, but not at locations over the ocean.

This specific PSC map was produced as part of a 5-step process:

1)  the various assignments (or agencies) to be included in the map were
    identified from the GMF,

2)  the assignments were categorized and coded for function/technology
    (by attaching a specific function and network code to each
    assignment),

3)  the coverage area was independently calculated for each transmitter
    in a network,

4)  PSC maps for each network were assembled from the transmitter
    coverage maps according to the applicable function codes for that
    network, and

5)  PSC maps for each network were combined into a PSC map for the
    agency or group of agencies.

The particular assignments included in this example were selected mainly
to show multiple "high-signal" areas, terrain effects, and low signal
rural areas.

Although the PSC map shown in Figure 7-1 provides much useful
information for visualizing how many signals could be seen by a mobile
user, this information is not necessarily the most useful information
for designing future alternative mobile radio systems. The most useful
type of system design information is usually in the form of the number
of users per square mile that could be served by a radio system. This
type of data is provided by ASC maps. The ASC map corresponding to the
PSC map shown in Figure 7-1 is shown in Figure 7-2.

As with the PSC map, the ASC maps shows the number of "independent
users" per square mile that current systems can support. A single
independent user represents a voice channel in use 24 hours a day. The
actual number of users supported can be quite large, since many users
could be distributed across a wide area and simultaneously listening to
a common signal. In addition, multiple talk groups could be time-sharing
that single voice channel, each talk group containing many users.

The ASC maps were computed by following the same five steps that were
used to compute the PSC map, except that a different algorithm was used
in step 4. The algorithm followed in step 4 calculated the total
effective area of a network and divided the PSC value at each location
by area (in square miles) of the network coverage. This means that a
network consisting of a single base station with a coverage area of
about 36-mile radius would provide about 4,000 square miles of coverage.
If there were a single transmitter at the base station, the PSC values
for each point of coverage would be "1" at each location. The ASC values
would be 1/4000 at each location, or 0.00025. Note that the total number
square miles of coverage times the ASC value gives the total number of
independent voice channels on the map.

![](media/image31.png){width="4.802777777777778in"
height="4.354166666666667in"}

Although the PSC and ASC maps appear quite similar, there is a major
difference in the numerical values that appear on the maps. Whereas the
maximum PSC value is 35, the maximum ASC value is .0129. Since the ratio
of these two values is about 2,600, this suggests that coverage area of
the typical site is about 2,600 square miles, corresponding to a
reception radius of about 29 miles.

The ASC map shows how many independent users per square mile could be
served by the mapped radio stations. The ASC data can be used when
future systems are designed with base station sites whose calculated
coverage areas are substantially different in size from the original
system coverage areas. For example, if two alternative future systems
were designed and System A employed base station sites having typical
coverage areas equal to 4,000 square miles, while System B sites had
coverage areas of 2,000 square miles, each site in System A would need
to be designed to carry about twice as much total traffic as each of the
System B sites.

The ASC maps are computed by finding the total coverage area of a given
transmitter and assuming that each independent transmitted frequency
could support one independent mobile user. If one assumes that the one
independent user is equally likely to be anywhere across the coverage
area, on the average, the ASC map would show that the ASC value of
average independent users per square mile is 1/A, where A equals the
total coverage area in square miles.

For example, if a particular base station with a coverage area of 3,000
square miles can support one independent user somewhere over that total
coverage area, the average density of independent users over the entire
3,000 square miles would be 1/3000 independent user per square mile =
0.00033. If another base station site provided coverage over only 500
square miles, the average density of users for that site would be 1/500
user per square mile = 0.002. Note that a base station with a small
coverage area provides ASC maps having larger average user density
values. The summation of average SC (user density) over a single
transmitter coverage area = 1 (i.e., one user).

Note that a single independent user can consist of many actual users
spread randomly across the coverage area (as long as all users are
listening to the same message). Moreover, the users could include
members from multiple talk groups, each talk group using the radio
channel at different times, as long as the total duration of the
multiple messages was less than 100 percent of the time.

The ASC values from a single channel or a single site add to ASC values
from other channels or other sites, depending on whether the additional
channels or sites contain independent message content. In the case of
overlapping coverage from semi-independent sites (e.g., multi-message
repeater networks, see Appendix A.), the ASC values are calculated first
as though there were no overlapping. Then, the ASC values are averaged
together in any areas of overlapping coverages. As with the PSC maps,
the ASC maps for agencies and larger groups of assignments are produced
by adding the ASC maps values for one network to the ASC map values for
other networks on a point-to-point location basis.

Most ASC maps will closely resemble the corresponding PSC maps, except
for a proportionality factor, P, which will be fairly constant over the
entire map. If P = PSC value/ASC value at any given location, the value
of P should be the approximate size of the coverage area of typical base
station transmitters in that area. Therefore, the value of P should
change over the map mainly if an agency uses different technologies or
design criteria for different geographical areas. For example,
mountaintop repeaters could give large coverage in rural areas, but
short-range, high capacity systems might be used in urban settings.

A single color scale has been used to plot all of the ASC and PSC maps.
This color scale was chosen to allow a quasi-logarithmic representation
of the ASC and PSC numerical values, such that the colors will allow a
useful differentiation of numerical values, whether a specific agency
map has relatively large or small numeric values. This convention should
aid in the reader being able to make a direct comparison in numeric
values among the various agency maps.

In addition, since the ASC maps typically contain values that are
5,000-10,000 times smaller than the corresponding PSC maps, the ASC map
numeric values have been multiplied by 10,000 times before being
plotted. This change was made to facilitate an understanding of the
similarities and differences between the corresponding ASC and PSC maps.
A common color scale, as used in the PSC maps, has also been used for
all of the ASC maps. A white background indicates "zero" SC (no
receivable signals) for both the ASC and PSC maps.

## Signal Capacity Maps for Federal Agencies

The following sections contain SC maps for various federal agencies.
Each section is formatted in approximately the same way and contains
approximately the same information. The agencies are mainly grouped by
federal department and arranged in alphabetical order. The Army, Navy,
and Air Force are grouped together under "Department of Defense." Some
agencies with less than 20 frequency assignments apiece are grouped
together as "Other Federal Agencies."

In addition to the individual departments, three sets of maps were made
for a combination of combined departments. These groupings include SC
maps for all federal agencies, for all of the agencies associated with
the new IWN and for all federal agencies minus the IWN agencies. These
additional three groupings are assumed to represent several logical
combinations of federal agencies that may be involved in building future
shared trunked systems.

Each agency/grouping includes a summary of assignment statistics for
that agency. These assignment statistics show how many assignments were
placed within each of the SCAP functional categories. Although wireless
links (F = 4), simulcast stations (F = 5), and area assignments
US/USA/US&P (F = 24) were included as potential categories of systems
during the determination of SCAP function codes, no GMF assignments with
these codes were identified for the Washington-area assignments. (In the
case of "area-type" assignments, these assignment types were eliminated
from the GMF assignments before the detailed function code determination
was started.) Therefore, the function codes F = 4, F = 5, and F = 24
were omitted from the function code summaries for each agency. Table 7-1
provides the total number of agency assignments and their function codes
that were used in the SCAP analysis and Table 7-2 provides the total
number of assignments and their function codes that were not used in the
SCAP analysis.

[]{#__RefHeading___Toc71359290 .anchor}Table 7‑5. Total Number of
Assignments with Function Codes Included in SCAP

  ------------------------------ ----------------- -----------------------
  **Total assignments included                     866
  in SCAP analysis**                               

  Individual base station        F = 3             247
  transmitter                                      

  Trunked network                F = 6             5

  Single-message repeater        F = 7             274
  network                                          

  Multiple-message repeater      F = 8             220
  network                                          

  Mobile/mobile user net         F = 9             120
  ------------------------------ ----------------- -----------------------

[]{#__RefHeading___Toc71359291 .anchor}Table 7‑6. Total Number of
Assignments with Function Codes Not Included in SCAP Analysis

  --------------------------- ------------------- -----------------------
  **Total assignments not                         1079
  included in SCAP analysis**                     

  Obsoleted link              F = 20              84

  Dedicated link              F = 21              333

  Receiver                    F = 22              418

  Receive-only station        F = 23              180

  Low power (10 mW or less)   F = 25              28

  Mobile-only replace by new  F = 26              36
  system                                          
  --------------------------- ------------------- -----------------------

The role of each agency is also described in general terms, with the
expectation that this description may be useful in helping the reader to
understand why the SC maps show more coverage at one location instead of
others.

The major features in each of the following sections are "agency" PSC
and ASC maps, which are displayed for each agency, department, or group
of agencies.

**Analysis of the Signal Capacity Maps By Agency**

### United States Department of Agriculture (USDA)

The locations of the USDA assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-2. That figure shows two major
transmitter concentrations, including national headquarter sites in and
near Washington, D.C., and national forest sites west of Washington
serving the Washington and Jefferson National Forests. The
urban/headquarter sites will use P25 digital technology, while the rural
national forest sites will use analog voice radios.

The PSC and ASC maps corresponding to current assignments are shown in
Figures 7-3 and 7-4, respectively. The PSC map shows that USDA has a
peak level of approximately 13, which indicates that there can be up to
13 individual signals concentrated around the USDA headquarters building
in Washington, D.C. The second concentration of signals is in the area
west of Washington, D.C., where up to three independent signals provide
coverage in the national forests. A line of points of higher incidental
coverage between Washington and the national forests occurs at high
elevation locations, where the forest coverage is supplemented with
occasional distant coverage from the Washington emitters. The ASC map
shows the same concentration of signals that the PSC shows, but now
represents a maximum average level of approximately .0080 signals per
square mile of coverage. Table 7-3 provides the USDA assignments and
function codes that were and were not included in the SCAP analysis.

![](media/image32.png){width="5.375in" height="4.642361111111111in"}

[]{#__RefHeading___Toc71359292 .anchor}Table 7‑7. U.S. Department of
Agriculture Assignments and Function Codes

  --------------- -------------------------------- -----------------------
  **Function**    **Description**                  **\# of Assignments**

  F = 3           Individual base station          11
                  transmitter                      

  F = 6           Trunked network                  0

  F = 7           Single-message repeater network  9

  F = 8           Multiple-message repeater        0
                  network                          

  F = 9           Mobile-only user net             2

  **Total                                          
  included = 22**                                  

  F = 20          Obsoleted link                   0

  F = 21          Dedicated link                   2

  F = 22          Receiver                         12

  F = 23          Receiver-only station            0

  F = 25          Low power (10 mW or less)        0

  F = 26          Mobile-only (replaced by new     0
                  system)                          

  **Total not                                      
  included = 14**                                  
  --------------- -------------------------------- -----------------------

![](media/image33.png){width="5.875in" height="5.375in"}

### United States Coast Guard (USCG) 

The locations of the USCG assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-4. That figure shows the major
transmitter concentrations along the Chesapeake Bay, including the
headquarter sites in and near Washington, D.C. The USCG currently uses
wideband simplex systems, but all current radios have narrowband digital
and analog capabilities. The USCG will be incorporating the 162-174 MHz
band into their new Rescue 21 digital system. The PSC and ASC maps
corresponding to current assignments are shown in Figures 7-5 and 7-6,
respectively.

The PSC map shows that USCG has a peak level of approximately 4,
indicating that there can be up to 4 individual signals around the
Baltimore Coast Guard Activity. The remainder of the USCG signals are
individual sites along the Chesapeake Bay, which represents a PSC of 1.
The ASC map shows the same concentration of signals that the PSC shows,
but now represents a maximum average level of approximately 0.0028. A
distinct difference, though, is the higher ASC in the area just south of
Salisbury, Maryland. This is due to the coverage area being smaller,
thus a higher ASC per square mile. Table 7-4 provides the USCG
assignments and function codes that were and were not included in the
SCAP analysis.

![](media/image2.png){width="5.770833333333333in"
height="5.148611111111111in"}

[]{#__RefHeading___Toc71359293 .anchor}Table 7‑8. U.S. Coast Guard
Assignment and Function Codes

  -------------- ------------------------------------- ---------------------
  **Function**   **Description**                       **\# of Assignments**

  F = 3          Individual base station transmitter   9

  F = 6          Trunked network                       0

  F = 7          Single-message repeater network       0

  F = 8          Multiple-message repeater network     0

  F = 9          Mobile-only user net                  5

  **Total                                              
  included =                                           
  14**                                                 

  F = 20         Obsoleted link                        0

  F = 21         Dedicated link                        0

  F = 22         Receiver                              0

  F = 25         Low power (10 mW or less)             0

  F = 26         Mobile-only (replaced by new system)  0

  **Total not                                          **0**
  included = 0**                                       
  -------------- ------------------------------------- ---------------------

![](media/image34.png){width="5.75in" height="5.1in"}

### United States Department of Commerce (DOC) 

The locations of the DOC assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-3. That figure shows the
concentrations for the two line offices that use this band; the National
Institute of Standards and Technology (NIST), with its heaviest
concentration around Gaithersburg, Maryland, and the National Weather
Service, which is located primarily in the mountainous area west of
Washington, and other sites located around the area. DOC currently uses
wideband analog radios, but will be transitioning to analog narrowband.
The PSC and ASC maps corresponding to current assignments are shown in
Figures 7-7 and 7-8, respectively.

The PSC maps show the largest peak usage of approximately 9 individual
signals around the Washington, D.C. and Gaithersburg, Maryland areas.
Some other notable remote areas have PSCs as high as 5. This is most
probably due to the higher elevation of mountain locations picking up
incidental signals from the Gaithersburg transmitters. The ASC map shows
the same concentration of signals as the PSC map but results in an
average of 0.0028 signals per square mile. Table 7-5 provides the DOC
assignments and function codes that were and were not included in the
SCAP analysis.

![](media/image35.png){width="5.625in" height="4.934722222222222in"}

[]{#__RefHeading___Toc71359294 .anchor}Table 7‑9. U.S. Department of
Commerce Assignments and Function Codes

  ----------------------- ----------------------------- ------------------
  **Function**            **Description**               **\# of
                                                        Assignments**

  F = 3                   Individual base station       9
                          transmitter                   

  F = 6                   Trunked network               0

  F = 7                   Single-message repeater       0
                          network                       

  F = 8                   Multiple-message repeater     1
                          network                       

  F = 9                   Mobile-only user net          1

  **Total included = 11**                               

  F = 20                  Obsoleted link                0

  F = 21                  Dedicated link                172

  F = 22                  Receiver                      0

  F = 23                  Receiver-only station         0

  F = 25                  Low power (10 mW or less)     0

  F = 26                  Mobile-only (replaced by new  172
                          system)                       

  **Total not included =                                
  172**                                                 

                                                        
  ----------------------- ----------------------------- ------------------

![](media/image36.png){width="5.884722222222222in"
height="4.895138888888889in"}

### United States Department of Defense (DOD)

The locations of the DOD assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-5. That figure shows that the
assignments are spread out over the entire area. However, this is in
relation to the various DOD facilities that are in and around the
Washington area. DOD currently utilizes various systems in this band to
support base security and fire, but there are plans to develop a joint
service, digital narrowband trunked system in the 380-400 MHz band. The
PSC and ASC maps corresponding to current assignments are shown in
Figures 7-9 and 7-10, respectively.

The PSC map shows that DOD has a peak level of approximately 36. This is
primarily concentrated around the Washington area due to the higher
concentration of DOD facilities in close proximity to Washington. There
are some higher capacity areas scattered northwest of Washington. This
may be due to higher elevations receiving incidental signals from
Washington and the surrounding area. The ASC map shows the same
concentration of signals, except that the highest is in the northern
section where it attains approximately 0.0228 signals per square mile.
This could be due to smaller coverage areas. Table 7-6 provides the DOD
assignments and function codes that were and were not included in the
SCAP analysis.

![](media/image37.png){width="5.552083333333333in"
height="4.958333333333333in"}

[]{#__RefHeading___Toc71359295 .anchor}Table 7‑10. U.S. Department of
Defense Assignments and Function Codes

  ------------------ --------------------------------- -------------------
  **Function**       **Description**                   **#of Assignments**

  F = 3              Individual base station           75
                     transmitter                       

  F = 6              Trunked network                   0

  F = 7              Single-message repeater network   9

  F = 8              Multiple-message repeater network 0

  F = 9              Mobile-only user net              24

  **Total included =                                   
  108**                                                

  F = 20             Obsoleted link                    0

  F = 21             Dedicated link                    39

  F = 22             Receiver                          6

  F = 23             Receiver-only station             5

  F = 25             Low power (10 mW or less)         9

  F = 26             Mobile-only (replaced by new      0
                     system)                           

  **Total not                                          
  included = 59**                                      
  ------------------ --------------------------------- -------------------

![](media/image38.png){width="5.552083333333333in"
height="4.958333333333333in"}

### United States Department of Energy (DOE)

The locations of the DOE assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-6. That figure shows that
transmitters concentrate in the Washington, D.C. headquarters and
Germantown, Maryland campus areas. DOE is currently operating with
digital narrowband equipment for their force protection operations, with
the rest of their systems being gradually changed over to analog
narrowband. The PSC and ASC maps corresponding to current assignments
are shown in Figures 7-11 and 7-12, respectively.

The PSC and ASC maps are virtually identical in presentation. The maps
show the highest peak of approximately 3, and highest average of
approximately 0.0012 signals per square mile in the area between
Washington and Germantown. Incidental signals are noticeable in the
higher elevations northwest and west of Washington. Table 7-7 provides
the DOE assignments and function codes that were and were not included
in the SCAP analysis.

![](media/image39.png){width="5.670138888888889in"
height="5.063888888888889in"}

[]{#__RefHeading___Toc71359296 .anchor}Table 7‑11. U.S. Department of
Energy Assignments and Function Codes

  ------------------ --------------------------------- -------------------
  **Function**       **Description**                   **\# of
                                                       Assignments**

  F = 3              Individual base station           0
                     transmitter                       

  F = 6              Trunked network                   0

  F = 7              Single-message repeater network   8

  F = 8              Multiple-message repeater network 0

  F = 9              Mobile-only user net              1

  **Total included =                                   
  9**                                                  

  F = 20             Obsoleted link                    0

  F = 21             Dedicated link                    34

  F = 22             Receiver                          0

  F = 23             Receiver-only station             0

  F = 25             Low power (10 mW or less)         2

  F = 26             Mobile-only (replaced by new      0
                     system)                           

  **Total not                                          
  included = 36**                                      
  ------------------ --------------------------------- -------------------

![](media/image40.png){width="5.659722222222222in"
height="5.058333333333334in"}

### Federal Aviation Administration (FAA)

The locations of the FAA assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-7. That figure shows that the
major transmitter concentration is in and near Washington, D.C., and
Baltimore, Maryland. The FAA has a major nationwide communications
system based on a regional concept that can tie all aviation and FAA
support facilities together. The FAA will be replacing their older
wideband system with a newer narrowband digital system. The PSC and ASC
maps corresponding to current assignments are shown in Figures 7-13 and
7-14 respectively.

The PSC shows that the highest peak signal is approximately 13. This is
consistent throughout the Washington/Baltimore area. This is due to
three major airports being located in relative close proximity to each
other. There are some mid-level and lower concentrations closely
surrounding the other regional airports in the study area. Incidental
signals from the Washington area are present in the higher elevations to
the west giving those areas a higher peak capacity than is supported by
actual transmitters. The ASC map shows that ASC reaches level of
approximately 0.0060 signals per square mile. Table 7-8 provides the FAA
assignments and function codes that were and were not included in the
SCAP analysis.

![](media/image41.png){width="5.659722222222222in"
height="5.032638888888889in"}

[]{#__RefHeading___Toc71359297 .anchor}Table 7‑12. Federal Aviation
Administration Assignment and Function Codes

  ------------------- ------------------------------- -------------------
  **Function**        **Description**                 **\# of
                                                      Assignments**

  F = 3               Individual base station         25
                      transmitter                     

  F = 6               Trunked network                 0

  F = 7               Single-message repeater network 16

  F = 8               Multiple-message repeater       3
                      network                         

  F = 9               Mobile-only user net            2

  **Total included =                                  
  46**                                                

  F = 20              Obsoleted link                  1

  F = 21              Dedicated link                  22

  F = 22              Receiver                        38

  F = 23              Receiver-only station           0

  F = 25              Low power (10 mW or less)       1

  F = 26              Mobile-only (replaced by new    1
                      system                          

  **Total not                                         
  included = 63**                                     
  ------------------- ------------------------------- -------------------

![](media/image42.png){width="5.779861111111111in"
height="5.097222222222222in"}

### United States Department of Interior (DOI)

The locations of the DOI assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-8. That figure shows the major
transmitter concentration around the national headquarter sites in and
near Washington, D.C. A lesser, but still notable peak signal
concentration is noted around Washington, D.C. DOI is currently
researching the feasibility of placing their law enforcement operations
on a digital narrowband trunked system. Their other operations will
convert to analog narrowband equipment. The PSC and ASC maps
corresponding to current assignments are shown in Figures 7-15 and 7-16,
respectively.

The PSC map shows concentrations of up to approximately 24 signals in,
and closely around, the Washington, D.C. area. Noticeable higher peak
levels are also noted around the immediate Washington, D.C. area. These
areas correspond to the national parks that reside in the study area.
The ASC map shows that the ASC reaches approximately 0.0096 signals per
square mile. Table 7-9 provides the DOI assignments and function codes
that were and were not included in the SCAP analysis.

![](media/image43.png){width="5.429861111111111in"
height="5.0784722222222225in"}

[]{#__RefHeading___Toc71359298 .anchor}Table 7‑13. U.S. Department of
Interior Number Assignments and Function Codes

  --------------------- ------------------------------- ------------------
  **Function**          **Description**                 **\# of
                                                        Assignments**

  F = 3                 Individual base station         15
                        transmitter                     

  F = 6                 Trunked network                 0

  F = 7                 Single-message repeater network 12

  F = 8                 Multiple-message repeater       63
                        network                         

  F = 9                 Mobile-only user net            4

  **Total included =                                    
  94**                                                  

  F = 20                Obsoleted link                  23

  F = 21                Dedicated link                  5

  F = 22                Receiver                        93

  F = 23                Receiver-only station           0

  F = 25                Low power (10 mW or less)       1

  F = 26                Mobile-only (replaced by new    36
                        system)                         

  **Total not included                                  
  = 158**                                               
  --------------------- ------------------------------- ------------------

![](media/image44.png){width="5.779861111111111in"
height="5.017361111111111in"}

### United States Department of Justice (DOJ)

The locations of the DOJ assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-9. That figure shows the major
transmitter concentration in Washington, D.C., with other transmitters
"scattered" throughout the study area. DOJ is in the process of
developing their next generation communication system, IWN. This system
will be a pseudo-nationwide P-25 digital trunked system. The PSC and ASC
maps corresponding to current assignments are shown in Figures 7-17 and
7-18, respectively.

The PSC map shows that the PSC for DOJ is an almost linear decrease in
peak signals moving out from Washington, D.C., with the highest
concentration of signals, approximately 70, in Washington, D.C. The
higher peaks in the diagonal line to the southwest are probably
incidental signals received in the higher attitudes from the metro area.
The ASC shows that DOJ reaches an ASC of approximately 0.0167 signals
per square mile. Table 7-10 provides the DOJ assignments and function
codes that were and were not included in the SCAP analysis.

![](media/image45.png){width="5.604166666666667in"
height="5.010416666666667in"}

[]{#__RefHeading___Toc71359299 .anchor}Table 7‑14. U.S. Department of
Justice Number Assignments and Function Codes

  --------------------- ------------------------------- ------------------
  **Function**          **Description**                 **\# of
                                                        Assignments**

  F = 3                 Individual base station         30
                        transmitter                     

  F = 6                 Trunked network                 0

  F = 7                 Single-message repeater network 139

  F = 8                 Multiple-message repeater       54
                        network                         

  F = 9                 Mobile-only user net            12

  **Total included =                                    
  235**                                                 

  F = 20                Obsoleted link                  52

  F = 21                Dedicated link                  13

  F = 22                Receiver                        191

  F = 23                Receiver-only station           175

  F = 25                Low power (10 mW or less)       4

  F = 26                Mobile-only (replaced by new    0
                        system)                         

  **Total not included                                  
  = 435**                                               
  --------------------- ------------------------------- ------------------

![](media/image46.png){width="5.708333333333333in" height="5.09375in"}

###  

### United States Capitol Police (USCP)

The locations of the USCP assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-11. That figure shows the major
transmitter concentration is in Washington, D.C. area. The USCP
currently uses a conventional wideband analog system. They will be
replacing these radios with narrowband analog radios. The PSC and ASC
maps corresponding to current assignments are shown in Figures 7-4 and
7-5, respectively.

The PSC map shows the highest PSC of approximately 5 in the Washington,
D.C. area. Some peak signals are evident to the west due to incidental
signals being present at higher elevations. The ASC map is virtually
identical map to the PSC, but shows the highest ASC to be approximately
0.0013 signals per square mile. The ASC is higher than would be expected
due to the concentrated operating area of the USCP. Table 7-11 provides
the USCP assignments and function codes that were and were not included
in the SCAP analysis.

![](media/image47.png){width="5.490277777777778in"
height="4.989583333333333in"}

[]{#__RefHeading___Toc71359300 .anchor}Table 7‑15. U.S. Capitol Police
Assignment and Function Codes

  --------------------- ------------------------------- ------------------
  **Function**          **Description**                 **\# of
                                                        Assignments**

  F = 3                 Individual base station         0
                        transmitter                     

  F = 6                 Trunked network                 0

  F = 7                 Single-message repeater network 14

  F = 8                 Multiple-message repeater       0
                        network                         

  F = 9                 Mobile-only user net            5

  **Total included =                                    
  19**                                                  

  F = 20                Obsoleted link                  0

  F = 21                Dedicated link                  0

  F = 22                Receiver                        6

  F = 23                Receiver-only station           0

  F = 25                Low power (10 mW or less)       0

  F = 26                Mobile-only (replaced by new    6
                        system)                         

  **Total not included                                  
  = 12**                                                
  --------------------- ------------------------------- ------------------

![](media/image48.png){width="5.509722222222222in"
height="4.926388888888889in"}

### United States Postal Service (USPS)

The locations of the USPS assignments within 100 miles of Washington,
D.C. were shown previously in Figure 4-12. That figure shows the major
transmitter concentration in Washington, D.C. The USPS currently uses
wideband analog radios but is in the processes of changing over to
narrowband. The PSC and ASC maps corresponding to current assignments
are shown in Figures 7-21 and 7-22, respectively.

The PSC map shows a PSC of approximately 13 in and immediately around
Washington, D.C. The peak level of three located to the north is due to
a smaller number of transmitters in the Harrisburg, Pennsylvania postal
facility. The higher peak levels that run in a diagonal line to the west
of Washington, D.C. are most likely incidental signals in the higher
elevations from Washington, D.C., and not representative of the actual
transmitters supporting that area. The ASC map gives a virtually
identical representation achieving an ASC of approximately 0.0072
signals per square mile. This higher level is concentrated due to the
use of in-building, small area coverage repeaters in the Washington,
D.C., postal facilities. Table 7-12 provides the USPS assignments and
function codes that were and were not included in the SCAP analysis.

![](media/image49.png){width="5.379861111111111in"
height="5.027083333333334in"}

[]{#__RefHeading___Toc71359301 .anchor}Table 7‑16. U.S. Postal Service
Assignments and Function Codes

  ------------------ --------------------------------- -------------------
  **Function**       **Description**                   **\# of
                                                       Assignments**

  F = 3              Individual base station           16
                     transmitter                       

  F = 6              Trunked network                   0

  F = 7              Single-message repeater network   6

  F = 8              Multiple-message repeater network 0

  F = 9              Mobile-only user net              14

  **Total included =                                   
  36**                                                 

  F = 20             Obsoleted link                    0

  F = 21             Dedicated link                    0

  F = 22             Receiver                          5

  F = 23             Receiver-only station             0

  F = 25             Low power (10 mW or less)         0

  F = 26             Mobile-only (replaced by new      0
                     system)                           

  **Total not                                          
  included = 5**                                       
  ------------------ --------------------------------- -------------------

![](media/image50.png){width="5.55in" height="5.096527777777778in"}

###  

### United States Department of Treasury (Treasury)

The locations of the Treasury assignments within 100 miles of
Washington, D.C. were shown previously in Figure 4-10. That figure shows
the major transmitters are in and around Washington, D.C., with smaller
transmitter sites "scattered" throughout the study area. Many of
Treasury's bureaus were transferred over to the Department of Homeland
Security and therefore will join the IWN with Justice. The PSC and ASC
maps corresponding to current assignments are shown in Figures 7-23 and
7-24, respectively.

The PSC map shows that Treasury's PSC is almost a linear taper-off from
Washington, D.C. throughout the whole area, while attaining a PSC of
approximately 35. A noticeable concentration of SC can be seen around
the capitol cities of Richmond, Virginia, and Wilmington, Delaware. The
ASC map shows the same concentration of signals as the PSC and attains
an ASC of 0.0129 signals per square mile. Table 7-13 provides the
Treasury assignments and function codes that were and were not included
in the SCAP analysis.

![](media/image51.png){width="5.458333333333333in"
height="4.976388888888889in"}

[]{#__RefHeading___Toc71359302 .anchor}Table 7‑17. U.S. U.S. Department
of Treasury Assignments and Function Codes

  ---------------- ------------------------------- ----------------------
  **Function**     **Description**                 **\# of Assignments**

  F = 3            Individual base station         5
                   transmitter                     

  F = 6            Trunked network                 5

  F = 7            Single-message repeater network 38

  F = 8            Multiple-message repeater       100
                   network                         

  F = 9            Mobile-only user net            17

  **Total included                                 
  = 165**                                          

  F = 20           Obsoleted link                  7

  F = 21           Dedicated link                  13

  F = 22           Receiver                        46

  F = 23           Receiver-only station           0

  F = 25           Low power (10 mW or less)       0

  F = 26           Mobile-only (replaced by new    0
                   system                          

  **Total not                                      
  included = 66**                                  
  ---------------- ------------------------------- ----------------------

![](media/image52.png){width="5.670138888888889in" height="4.75in"}

### United States Department of Veterans Affairs (VA)

The locations of the VA assignments within 100 miles of Washington, D.C.
were shown previously in Figure 4-13. That figure shows two major
transmitter concentrations, including national headquarter sites in and
near Washington, D.C., and a major VA facility in northeastern Maryland.
The urban/headquarter sites will be changing over to the 1CommWireless
system, a digital trunked system, while the other sites have already
transitioned to analog narrowband radios. The PSC and ASC maps
corresponding to current assignments are shown in Figures 7-25 and 7-26,
respectively.

The PSC map shows that the higher peak signals of approximately 7 are
more in the northeastern portion of the map. This is caused by an
overlapping of transmitter signals from facilities in Pennsylvania,
Maryland, and Delaware. The diagonal line to the west of Washington is
most likely incidental signals in the higher elevations. The ASC map
mirrors the peak map in that the highest average capacity of
approximately 0.0036 signals per square mile is in that same area to the
northeast. Table 7-14 provides the VA assignments and function codes
that were and were not included in the SCAP analysis.

![](media/image53.png){width="5.55in" height="5.095138888888889in"}

[]{#__RefHeading___Toc71359303 .anchor}Table 7‑18. U.S. Department of
Veterans Affairs Assignments and Function Codes

  ---------------- ------------------------------- ----------------------
  **Function**     **Description**                 **\# of Assignments**

  F = 3            Individual base station         0
                   transmitter                     

  F = 6            Trunked network                 0

  F = 7            Single-message repeater network 5

  F = 8            Multiple-message repeater       6
                   network                         

  F = 9            Mobile-only user net            6

  **Total included                                 
  = 17**                                           

  F = 20           Obsoleted link                  0

  F = 21           Dedicated link                  7

  F = 22           Receiver                        5

  F = 25           Low power (10 mW or less)       0

  F = 26           Mobile-only (replaced by new    0
                   system)                         

  **Total not                                      
  included = 12**                                  
  ---------------- ------------------------------- ----------------------

![](media/image54.png){width="5.670138888888889in" height="5.08125in"}

###  

### Other Agencies

The category of "other agencies" includes several smaller agencies and
other agencies with the majority of transmitters located in the
immediate Washington, D.C. area. Their assignments were shown previously
in Figure 4-14. That figure shows a few separate locations outside of
Washington, D.C. Most the various agencies utilize various forms of
analog wideband radios while some have already transitioned to
narrowband analog or digital. The PSC and ASC maps corresponding to
current assignments are shown in Figures 7-27 and 7-28, respectively.

The PSC map show a large PSC, approximately 55, concentrated in and
around Washington, D.C. This is indicative of the concentration of the
various agencies conducting most, if not all of their LMR operations in
and around Washington, D.C. There are some higher peaks to the northwest
and west, but this is probably due to incidental signals at higher
elevations from Washington, D.C., rather than being caused by actual
transmitters. The ASC shows the same coverage pattern with the highest
ASC at approximately 0.040 signals per square mile. This is a relatively
large figure due to the majority of operations concentrated in the
Washington, D.C. area. Table 7-15 provides the "other agency"
assignments and function codes that were and were not included in the
SCAP analysis.

![](media/image55.png){width="5.5625in" height="4.979166666666667in"}

[]{#__RefHeading___Toc71359304 .anchor}Table 7‑19. "Other Agencies"
Assignments and Function Codes

  ------------------ --------------------------------- -------------------
  **Function**       **Description**                   **\# of
                                                       Assignments**

  F = 3              Individual base station           45
                     transmitter                       

  F = 6              Trunked network                   0

  F = 7              Single-message repeater network   18

  F = 8              Multiple-message repeater network 27

  **Total included =                                   
  90**                                                 

  F = 20             Obsoleted link                    1

  F = 21             Dedicated link                    26

  F = 22             Receiver                          16

  F = 23             Receiver-only station             0

  F = 25             Low power (10 mW or less)         11

  F = 26             Mobile-only (replaced by new      0
                     system)                           

  **Total not                                          
  included = 54**                                      
  ------------------ --------------------------------- -------------------

![](media/image56.png){width="5.552083333333333in"
height="4.958333333333333in"}

### All Federal Agencies

PSC and ASC maps were developed to give an overall "picture" of what the
total federal usage looks like in the study area. As with all the
individual agency maps, the highest peak, approximately 268, and
average, approximately 0.1000, center in and around the Washington, D.C.
area. This stands to reason, as all the agency headquarters are located
in D.C. The PSC and ASC maps corresponding to current assignments are
shown in Figures 7-29 and 7-30, respectively. Table 7-16 provides all
federal agencies assignments and function codes that were and were not
included in the SCAP analysis.

![](media/image57.png){width="5.552083333333333in"
height="4.947916666666667in"}

[]{#__RefHeading___Toc71359305 .anchor}Table 7‑20. All Federal Agencies
Assignments and Function Codes

  ------------------ --------------------------------- -------------------
  **Function**       **Description**                   **\# of
                                                       Assignments**

  F = 3              Individual base station           247
                     transmitter                       

  F = 6              Trunked network                   5

  F = 7              Single-message repeater network   274

  F = 8              Multiple-message repeater network 220

  F = 9              Mobile-only user net              120

  **Total included =                                   
  866**                                                

  F = 20             Obsoleted link                    84

  F = 21             Dedicated link                    333

  F = 22             Receiver                          418

  F = 23             Receiver-only station             180

  F = 25             Low power (10 mW or less)         28

  F = 26             Mobile-only (replaced by new      36
                     system)                           

                     **Total not included = 1079**     
  ------------------ --------------------------------- -------------------

![](media/image58.png){width="5.552083333333333in"
height="4.947916666666667in"}

### Integrated Wireless Network (IWN) (United States Departments of Justice, Treasury and Homeland Security)

The PSC and ASC maps for this section are a combination of the agencies
that will be the initial users of the IWN. These agencies will include:
Federal Bureau Investigation (FBI), U.S. Marshall Service (USMS), Bureau
of Prisons (BOP), Drug Enforcement Administration (DEA), Alsohol,
Tobacco and Firearms (ATF), Customs and Border Protection, Immigration
and Naturalization Services, General Services Administration (GSA),
Transportation Security Administration(TSA), and the U.S. Secret Service
(USSS).

The PSC map shows that the main concentration of peak signals,
approximately 84, is in close vicinity to Washington, D.C. The ASC shows
the same properties, attaining a highest average capacity of
approximately 0.0250 signals per square mile. Table 7-17 provides the
IWN assignments and function codes that were and were not included in
the SCAP analysis.

![](media/image59.png){width="5.5625in" height="4.979166666666667in"}

[]{#__RefHeading___Toc71359306 .anchor}Table 7‑21. IWN Assignments and
Function Codes

  ------------------ ------------------------------- --------------------
  **Function**       **Description**                 **\# of
                                                     Assignments**

  F = 3              Individual base station         35
                     transmitter                     

  F = 6              Trunked network                 5

  F = 7              Single-message repeater network 149

  F = 8              Multiple-message repeater       85
                     network                         

  F = 9              Mobile-only user net            24

  **Total included =                                 
  298**                                              

  F = 20             Obsoleted link                  56

  F = 21             Dedicated link                  27

  F = 22             Receiver                        217

  F = 23             Receiver-only station           175

  F = 25             Low power (10 mW or less)       4

  F = 26             Mobile-only (replaced by new    0
                     system)                         

  **Total not                                        
  included = 479**                                   
  ------------------ ------------------------------- --------------------

![](media/image60.png){width="5.552083333333333in"
height="4.947916666666667in"}

### All Federal Agencies minus IWN

The last two maps represent the federal users in the study area minus
the participants of the IWN. Once again, the highest peak, approximately
190, and average, approximately 0.0700, capacity signals are centered
nearest Washington, D.C. This is primarily due to the various agencies'
headquarters being located within this area. Table 7-18 provides the
Non-IWN assignments and function codes that were and were not included
in the SCAP analysis.

![](media/image61.png){width="5.552083333333333in"
height="4.927083333333333in"}

[]{#__RefHeading___Toc71359307 .anchor}Table 7‑22. Non-IWN Assignments
and Function Codes

  ------------------ ------------------------------- ---------------------
  **Function**       **Description**                 **\# of Assignments**

  F = 3              Individual base station         212
                     transmitter                     

  F = 6              Trunked network                 0

  F = 7              Single-message repeater network 125

  F = 8              Multiple-message repeater       135
                     network                         

  F = 9              Mobile-only user net            96

  **Total included =                                 
  568**                                              

  F = 20             Obsoleted link                  28

  F = 21             Dedicated link                  306

  F = 22             Receiver                        201

  F = 23             Receiver-only station           5

  F = 25             Low power (10 mW or less)       24

  F = 26             Mobile-only (replaced by new    36
                     system)                         

  **Total not                                        
  included = 600**                                   
  ------------------ ------------------------------- ---------------------

![](media/image62.png){width="5.552083333333333in"
height="4.958333333333333in"}

Page 7-42/Blank

#  SUMMARY OF FINDINGS 

The following section provides a summary of findings of the Phase 1
study that was based on a SCAP for the 162-174 MHz band in the vicinity
of Washington, D.C. The SCAP produced results in terms of PSC and ASC
contours maps for the various federal agencies.

1.  The SCAP was developed to provide a theoretical basis for
    understanding the services provided to federal LMR users in the
    162-174 MHz band within a 100-mile radius of Washington, D.C. Radio
    services not provided by the fixed base station infrastructure were
    excluded from this study by assigning appropriate function codes.

2.  Data from the GMF, supplemented with information obtained from the
    agencies, allowed the SCAP to provide PSC and ASC maps for federal
    agencies in the 162-174 MHz band in the Washington, D.C. area. These
    results can provide an improved understanding of federal LMR
    services, and can be applied in the design of possible future LMR
    systems with higher spectrum efficiency and effectiveness than
    current systems.

3.  Although SCAP provides a useful tool with which to compare the
    services provided by current and future systems, it does not provide
    any measure of absolute spectrum efficiency achieved by either
    system.

Table 8-1 provides a summary of the maximum PSC map values and the total
number of transmitters included in the SCAP for each federal agency and
some groups of agencies. The maximum PSC map value shows what the
highest level of PSC was in the PSC map for each agency, e.g., a value
of "35" indicates that some locations provided coverage for as many as
35 separate radio channels. The "included transmitter" column shows how
many LMR transmitters were included in the SC maps for each agency.
Agencies with large numbers of radios and high PSC values included DOD,
DOI, DOJ, and Treasury. These agencies had extensive LMR networks that
could provide as many as 24-70 independent LMR channels in some
locations. The All-Agency group contained a total of 866 transmitters
and a maximum PSC map value of 268. Even the group of IWN agencies had
only about 35 percent of the total transmitters, with almost 65 percent
of the remaining for the other agencies. This means that even the
largest agencies represent only a small percentage of the total number
of federal government transmitters. The increased scale of an all-agency
operation could provide substantial advantages, if future systems
provide meaningful economy of scale factors.

[]{#__RefHeading___Toc71359308 .anchor}Table 8‑23. Maximum Peak Signal
Capacity and Included Transmitters

  ----------------------- ----------------------- -----------------------
  **Agency**              **Max Peak SC Map       **\# of Included
                          Value**                 Transmitters**

  Agriculture             13                      22

  U.S. Coast Guard        4                       14

  Commerce                9                       10

  Defense                 38                      108

  Energy                  3                       9

  FAA                     17                      46

  Interior                24                      94

  Justice                 70                      235

  U.S. Capitol Police     5                       19

  U.S. Postal Service     13                      36

  Treasury                35                      165

  Other Agencies          55                      90

  All Agencies            268                     866

  IWN Agencies            84                      298

  Non-IWN Agencies        190                     568
  ----------------------- ----------------------- -----------------------

4.  Many agencies have no coverage adjacent to the immediate Washington,
    D.C. area. Such agencies may gain much greater coverage, extending
    their coverage to 93 percent of all locations within the 200-mile
    square area that was analyzed, if they could share the existing LMR
    radio systems of other federal agencies. (Of course, it is also
    possible that many agencies do not need any coverage outside their
    current coverage areas.) Agencies with small numbers of users, but
    needing wide coverage would probably find it much less expensive to
    get the required service with some type of future shared system.
    Analysis of PSC data from the All-Agency map shows that 93 percent
    of locations had coverage from at least one transmitter, and 63
    percent of locations had coverage from at least ten transmitters.
    Ten percent of locations had coverage from at least 100
    transmitters, almost four percent of the locations had coverage from
    at least 200 transmitters, and some locations received more than 265
    transmitters. The few areas without any coverage were mainly in the
    corners of the map beyond the 100-mile radius circle, which may be
    largely due to "edge" effects inherent in the modeling.

5.  The SCAP encompasses only the base-to-mobile aspects of current
    radio systems. A future radio system, as a minimum, would need to
    duplicate the mobile-to-base and mobile-to-mobile capabilities of
    current radio systems. The base-to-mobile information provided by
    the SCAP model can help define the necessary corresponding
    mobile-to-base capabilities. However, the inferred mobile-to-base
    capability will need to be further studied to determine specific
    requirements (including in-building, portable coverage), so that the
    needed mobile-to-base capabilities can be completely included in the
    design specifications.

6.  Although the SCAP provides very useful information about the
    geographic locations where current radio services are provided to
    mobile radios, it provides no data showing where the served mobile
    users are located. A computed coverage area for a specific base
    station transmitter shows all of the locations where a mobile user
    could possibly receive a usable signal, but it does not necessarily
    mean that the mobile users actually are located uniformly over the
    computed coverage area when they receive that signal. For example, a
    given transmitter located near the center of Washington, D.C. could
    be used solely to provide in-building coverage, (e.g., the four
    sub-basement parking levels) for buildings in the middle of the
    city, or it could possibly be used solely to provide coverage to
    mobile units operating in the distant suburbs. Since SCAP provides
    no clue as to which set of mobile users such a system is designed to
    serve, an alternative future system might be unnecessarily designed
    to serve both sets of users.

7.  The SCAP analysis does not provide any information on the amount of
    radio traffic carried on each channel. Therefore, although it may be
    known that 23 independent radio signals are available at a given
    location, there is no information about how much of the time these
    23 channels are actually used, or when the channels are used. This
    type of data could be obtained by measuring actual LMR radio traffic
    data, using equipment like the NTIA/ITS Radio Spectrum Measurement
    System (RSMS).

8.  The SCAP analysis (and the associated agency interviews) ensured
    that the analyzed LMR systems included no aspects of agency
    operation that would necessarily be disadvantaged by combining
    operations with other agencies, assuming that the required
    availability of service, reliability, response time, and protection
    of sensitive information could be provided by some future system.
    Technical functions of agency operation that could not be
    incorporated within the SCAP (e.g., mobile-to-mobile operation) were
    excluded from this analysis by the assignment of suitable function
    codes. Thus, it appears that the existing functions provided to
    agencies by the assignments included in the PSC and ASC maps could
    be provided by a future shared system. Whether such a future shared
    system could provide all of the desired features at a reduced cost,
    or with other advantages, remains to be seen. These details will be
    investigated in Phase 2 of the study. Similarly, the policy and
    managerial problems associated with possible future shared systems
    may not be trivial to resolve.

9.  The GMF, in its current form, did not always provide sufficient
    information to permit the assignment of function codes as an input
    to the SCAP model. Additional information on system operations was
    often required from the various agencies.

10. There are various existing programs, initiatives, and studies on
    improving spectrum efficiency within the federal government. These
    programs will continue to provide a context within which future
    improvements to federal spectrum efficiency will need to adapt and
    conform. Such programs may be particularly important to consider in
    assessing the feasibility of various future LMR system designs
    proposed in Phase 2 of this overall study, as well as the scheduling
    and priority of the related studies.

11. It is envisioned that the SCAP results developed for Phase 1 will
    help to quantify the advantages and disadvantages involved in a
    future radio system, as well as to provide insights to the best
    architectures and technologies to be employed and the circumstances
    under which maximum effectiveness would be achieved.

#####  DESCRIPTION OF SIGNAL CAPACITY ANALYSIS PROGRAM

A crucial piece of the analysis of existing agency radio services is the
determination of the current geographical SC of existing radio systems
providing communications to existing federal mobile users. The resulting
PSC and ASC maps will be the starting point for the design of several
alternative future radio systems to be designed in Phase 2 of this
study. Specifically, the PSC maps will show how many independent LMR
channels can currently be received by mobile users, cumulatively, for
all agencies, at any location within a 100-mile radius of Washington,
D.C. The ASC maps will show how many average independent users per
square mile can be supported by the current radio systems. It is assumed
that any alternative future radio system that is capable of providing a
similar, or greater, SC for all locations of the maps could be viewed as
providing services that are equal to or greater than the services
provided by current radio systems. The following section discusses, in
detail, the computation algorithm for the SCAP.

###### COVERAGE ANALYSIS OF CURRENT RADIO SYSTEMS

In computing the SC maps for each network, the first step is to compute
the coverage area for each included transmitter. This will require
transmitter and antenna information that can be used to compute
predicted signal strength as a function of geographical location, using
a terrain-based propagation model. Any predicted field strengths in
excess of an established limit may be presumed to constitute "coverage."
Since all of these network SC maps are intended to be added to other
network SC maps, it may be useful to compute the field strength at a
standard set of geographical locations, namely a fixed standard set of
locations with 1-mile spacing over an approximate 100-mile radius
centered on Washington, D.C. These geographical locations remain fixed
at a standard set of locations, instead of being located relative to
each transmitter location.

The field strength, S, from a transmitter can be calculated as:

S = P + G -- R - L + 74.8

Where: S = field strength in decibels above 1 microvolt/meter (dB µV/m),

P = transmitter power in decibels above 1 Watt (dBW),

G = transmitting antenna gain in decibels above isotropic (dBi),

R = 20 log distance from transmitter (kilometers), and

L = Propagation loss (dB), compared with free-space.

The transmitter power and transmitting antenna gain, as well as antenna
location and elevation, come from the GMF records. The propagation loss
is calculated by using the Longley-Rice model with the required terrain
data.[^64]

All systems will be analyzed to show coverage for a single field
strength level of X µV/m for a certain percentage of locations and a
certain percentage of time, assuming typical mobile radio parameters.
For these coverage predictions, the terrain-dependent Longley-Rice model
was used, giving predicted propagation path losses for 1-mile increments
over a 200-mile square centered on Washington, D.C. The process of
selection of proper parameters for field strength and percentages of
time and locations is described in the next paragraphs.

Proper coverage analysis parameters for this modeling effort would be
best selected to reflect the functional/operational requirements of each
of the respective radio systems. On this basis, a radio transmitter used
to service handheld radios that may be used inside large office
buildings and provide very reliable continuous service may require a
field strength of 30-100 µV/m outside the building. On the other hand,
the need to intermittently maintain contact with a dispatcher at a
maximum distance using a mobile transceiver might be accomplished with a
signal level as little as 1 µV/m. Although there is a large difference
between these two field strength requirements, it still may
theoretically be possible to divide transmitters into categories that
would show which field strength value should be used in the coverage
analysis for each transmitter. However, the main purpose of the SC
analysis is to develop a definition of coverage that is interchangeable
between various systems. Otherwise, a future application of the SC data
may attempt to provide a 1 µV/m signal to an operational mission that
needed a 100 µV/m signal. Therefore, it was necessary to choose a single
definition of coverage that could be used for all systems.

In addition to the decision about field strength values, there are
similar choices concerning the values of "reliability" and "confidence"
associated with the field strength values. A propagation model like
Longley-Rice provides predictions for mobile radio signal strength, S,
from base stations in the form of: "There is a confidence of at least C
percent that the received mobile radio signal will be above S µV/m for R
percent of the time." Since this propagation model is being applied to a
mobile/portable system where it is assumed that the mobile unit is
moving, the R factor (reliability) includes the effects of moving
through time as well as moving across geography. Choosing a higher value
for reliability (R) or confidence (C) has a similar effect to choosing a
higher value of field strength (S) (e.g., at a given location, a
confidence of getting at least a small signal with very high reliability
almost all of the time).

Figure A-1 shows the relative coverage areas of a group of transmitters,
analyzed using different combinations of reliability, confidence, and
field strength as the definition of "coverage" when generating these PSC
maps. These 200-mile square PSC maps show how many transmitters can be
received at each location on the map, using the same color scale on all

maps to show the number of receivable transmitters. The PSC coverage
maps are arranged in 3 columns, having 4 rows each. The first column
(left-most) was analyzed for a reliability of 50 percent and a
confidence of 50 percent for 4 different field strength values. The
middle column was analyzed for a reliability of 90 percent and a
confidence of 50 percent; the right-most maps to show the number of
receivable transmitters. The PSC coverage maps are arranged in 3
columns, having 4 rows each. The first column (left-most) was analyzed
for a reliability of 50 percent and a confidence of 50 percent for 4
different field strength values. The middle column was analyzed for a
reliability of 90 percent and a confidence of 50 percent; the right-most
column was analyzed for a reliability of 90 percent and a confidence of
90 percent. All three columns were analyzed for identical field strength
limits. The top row assumed that "coverage" required a signal of at
least 1 µV/m, the second row assumed that "coverage" required a signal
of at least 2 µV/m, the third row showed coverage based on 5 µV/m, and
the bottom ![](media/image63.png){width="6.492361111111111in"
height="7.5784722222222225in"}

In the preceding figures, the maps show that the coverage areas for a
set of transmitters decrease greatly when the receiver/service requires
higher reliability, higher confidence, or higher field strength. As
described in the following paragraphs, the decision was eventually made
to use a coverage criterion of reliability of 90 percent, confidence of
50 percent, and field strength of 10 µV/m.

Initially, it should not make any difference which threshold value and
statistics are selected, since the major purpose of the SC model is to
assure that the coverage of the new system(s) is at least as good as the
coverage of the current systems. As long as the old and new systems are
tested with the same coverage parameters, use of exact values is not so
important. Unfortunately, the preceding statement is not quite true. The
problem is that the SC model does not "know" what is the intended use of
a given radio system. If the intended use of a current radio system is
to provide some coverage at large distances, the SC modeling should
capture that use in its analysis, since that use will need to be
provided in a future system. If the extended rural coverage is merely an
unintended consequence of a transmitter intended to provide highly
reliable in-building communication in urban areas, then the SC modeling
should not include it and a future system should not need to provide it.
If all the future systems used the same base station placement as
existing systems to provide duplicate coverage, there would be less need
to determine the intended coverage of transmitters, since duplicating
the urban coverage would also tend to duplicate the rural coverage
whether it was needed or not. However, since some of the alternative
future systems will use different architectures and cell sizes, there is
less assurance that close-in and distant coverage will be similarly
related in old and new systems.

The selection of a signal level near 1 µ/m was assumed to be
inappropriate for several reasons. Many public safety personnel use
portable handheld receivers, whose overall sensitivity in normal
operating circumstances is likely to be as much as 3 µV/m. This high
signal requirement is caused partly by less-efficient small antenna
systems and partly by absorption and shielding by personnel holding the
radio. The problems become even more pronounced when such handheld
receivers are operated inside buildings, which can provide 10-30 dB of
additional losses to radio signals. The general requirements of public
safety personnel are to have higher reliability and availability of
communications. Finally, the use of very low occupancy thresholds in
analyzing current systems produced a strange anomaly. In some
circumstances, the highest SC values occurred in rural locations where
few users were present. The use of very low threshold values caused
urban transmitters to produce "coverage" in some quite distant rural
areas. In fact, there were some high-elevation rural locations where the
weak signals from multiple distant urban areas could add together to
produce coverage by total numbers of signals higher than in the core of
any single urban area. Further analysis revealed that most urban
transmitters were not installed with the intention of providing
intermittent and unreliable coverage to large numbers of non-existent
rural users. This "rural peak" effect seems to disappear for occupancy
thresholds greater than 5µV/m.

However, most rural service is delivered to public safety users with
mobile radios or operating outdoors with handheld radios. Such
situations can provide good reception with signal levels of less than 3
µV/m, though rugged terrain might produce deep signal shadows that often
had much less signal than that. Since it seems reasonable to include any
signal levels that could be expected, to provide usable service to
federal users, an amplitude level near 3 µV/m could be assumed as an
appropriate coverage limit.

After considering many factors, coverage was eventually defined by using
a field strength of 10 µV/m, providing 90 percent reliability at a 50
percent confidence. This set of parameters corresponds to the bottom map
in the middle column in Figure A-1. For simplicity, this definition was
used for all radio technologies, even though some signal modulation
technologies require more or less signal power for operation. The SC
summary maps in Section 7 of this report were computed using the above
definition for coverage.

###### PEAK AND AVERAGE SIGNAL CAPACITY MAPS

This section contains a description of the algorithms used to calculate
the PSC and ASC maps for networks having various function codes. Note
that some network types may have different function codes, but use the
same algorithm for computing the SC network maps. These multiple
function codes are useful because the function codes are also intended
to be used later in summarizing various statistical changes in how
frequencies are used and the different function codes will facilitate
some of this future analysis. Two distinct types of SC maps will be done
for each network: a PSC and an ASC map. These two representations of SC
will place two types of bounds on the SC provided by current systems.
The PSC map produces results that assume that all users might be
concentrated into a single small geographical area. Alternatively, the
ASC maps assume the most benign geographical distribution of users, with
users spread out as evenly and uniformly as possible. The ASC maps
provide "users per square mile" data that is intended to scale base
station traffic proportional to the coverage area of a given base
station. Under the ASC assumptions, a base station with ten percent of
the coverage would be expected to carry ten percent of the traffic.
Designs using PSC data would not scale with coverage area, since all of
the possible users could be crowded into that particular ten percent of
the coverage area.

Any alternative future network would be required to assume some
geographic distribution of users in its design. The calculation of both
ASC and PSC maps provides two different extremes of rules, either of
which might furnish a partial basis for new system design, but probably
both should be used. Consider the implications of designing an
alternative future system on the basis of ASC map values. Since the ACS
values provide data on users per square mile, the design traffic loading
on a given site would scale proportional with the area to which the site
is providing coverage. If the new alternative system uses sites with the
coverage areas smaller than current site coverage areas, the design
traffic loading per site would be proportionally smaller than current
traffic loading per site. However, if the future alternative design uses
sites with larger coverage areas, presumably the new sites would be
designed to carry proportionately larger traffic loads than the old
sites. Under these conditions, the design criteria based on the ASC maps
would be larger than the design criteria based on the PSC maps.
Therefore, the PSC maps assume that the number of users does not change
with coverage area, but remains constant with all possible users
concentrated into a single location. Furthermore, a design based on the
PSC maps would require a constant design site traffic load that would
not change with coverage area of the site. This circumstance would
require supporting the full PSC number of users within even very small
cells, but the use of larger-than-current cells would require fewer
channels based on PSC data than on ASC data.

Thus, the PSC and ASC maps represent the worst-case and best-case
situations from the standpoint of designing alternative radio systems,
depending on whether the alternative future systems use smaller or
larger cells than the current systems. The exact design criteria that
will be used to size possible future system designs is not yet known,
but it must surely lie between these two bounding cases. The Phase 2
report on the design of possible alternative future systems will more
fully consider this aspect of system design.

SC maps are computed in two distinct stages. First, the PSC and ASC maps
for individual networks are calculated using the GMF data, the function
code and corresponding algorithms for that specific network, and
applicable propagation models. Once the PSC and ASC maps have been
calculated for a specific network, these maps can be combined and
recombined on a strictly additive basis, without regard for the specific
function codes that were originally used to compute the maps. PSC maps
are combined with other PSC maps, adding numeric values on a location
point-by-point basis to get a new cumulative PSC map. Similarly, ASC
maps are combined with other ASC maps, adding numeric values on a
location point-by-point basis to get a new cumulative ASC map.
Cumulative SC maps can be combined with other cumulative SC maps or
network SC maps to get new SC maps representing more extensive
combinations of assignments or agencies.

The PSC will be determined by placing a "1" in each location where one
signal from a base station can be received. If a base station has ten
independent signals that can all be received at a given location, a
value of "10" would be placed at that location. If a receiver at a given
location could receive nine signals from one base station and seven
different signals from another base station, a value of "16" would be
put in that location. This network PSC map shows the peak number of
independent signals that can be received at each location. When a
cumulative PSC map shows the combined PSC for all the networks belonging
to a single agency, the map would indicate the maximum number of
independent signals that can be received from all networks belonging to
that agency at each location. Similarly, when the PSC maps for each
agency are combined to give a cumulative PSC map for all agencies, that
map will contain numbers showing the maximum number of independent radio
signals that could be received from all agencies at each location. PSC
values will all be positive integers, possibly as large as several
hundred.

The ASC map is computed by normalizing the coverage area of a base
station transmitter to give the average use per unit area (square mile)
that could be obtained from a given transmitter. If a transmitter, "A,"
has twice the coverage area of another transmitter, "B," the average use
per unit area for all areas of transmitter "A" coverage will be half of
the average use of the transmitter "B" coverage area. The coverage area
of a transmitter multiplied by the ASC value at each location of
coverage will give a number that represents the total number of
independent transmitters. The ASC value of a single transmitter is
computed by modeling the coverage of that transmitter and putting a "1"
at each location having coverage (note that this is identical to the PSC
map for that transmitter). The total number of locations having a "1"
are counted and placed into the value "K." Since the computed locations
are one mile apart, K represents the transmitter coverage area in square
miles. Then the "1" at each coverage location is replaced with the value
"1/K." If a given base station had ten independent transmitters having
the same coverage area, the ASC map for that base station would have a
value of "10/K" for the ASC at each coverage location. ASC values will
tend to be small positive fractions, typically in the range of .000l to
0.1. However, to make it easier to read ASC maps, the actual ASC values
plotted on the ASC maps have been multiplied by 10,000. This gives ASC
maps values ranging between 0 and 600.

The cumulative ASC map for all networks belonging to a single agency can
be computed by adding the values at each corresponding geographical
location from all of the ASC maps for each independent network for that
agency. Similarly, the summary ASC map for all agencies can be generated
by adding together the ASC values at each corresponding location for
each of the summary ASC maps for each agency. If the values for every
geographical location on the cumulative ASC map are summed, it will
represent the total number of independent radio transmitters represented
by the map, adjusting for the fact that the ASC map values have been
multiplied by 10,000.

These two SC maps represent the maximum and minimum signal capacities
that need to be provided by the new radio system. If all radio networks
included in this analysis had identical coverage areas (same total area,
not the identical geography), the maps would be identical (except that
the ASC map would have values equal 1/K times the corresponding location
values in the PSC map). The physical significance of the PSC and ASC
maps is that the PSC map shows the capacity that the new comparable
network would need to handle if all possible users were concentrated at
a single location on the map. The ASC shows the capacity per square mile
of coverage that the new comparable system would need if all users were
spread out as evenly as possible over the coverage locations on the map.

The ASC and PSC maps do not represent realistic estimates. The actual SC
values would be somewhere between the two. These two types of SC maps
suggest the extreme range of circumstances that could be supported by
the present infrastructure. Even if a comparable infrastructure was
built to match the PSC maps, there would be no assurances that certain
circumstances would not overload the system. It would only ensure that
the comparable system would not have fewer capabilities than the current
one. In a wide range of circumstances, a properly designed comparable
system would be expected to work considerably better than the current
system.

###### FUNCTION CODE DESCRIPTIONS AND ALGORITHMS

SC modeling begins by dividing all GMF assignments in the geographical
area of concern into various classes. The GMF data and agency
consultation is necessary to generate a "function code" for each
assignment. The function code indicates how each assignment is to be
analyzed by the SCAP. The function code (F, N) has two parameters. "F"
denotes the function served by that assignment; "N" is an integer that
identifies the specific network of which that assignment is a
constituent part. The actual value of "N" has no significance except to
identify assignments that are parts of the same network. Each assignment
belongs to exactly one network; all assignments belonging to the same
network will be given the same value of "N." Networks containing only a
single assignment do not exercise any network qualities and are given a
value of N = 0. N = 0 indicates that no other assignment belongs to a
given network.

**Division of Assignments by Function (F):** This variable is associated
with the first parameter in the function code for each assignment. The
function codes for assignments not included in the SC analysis are also
specified, even though they all produce the same result (no action).
This is because it is important that it is correctly understood why such
assignments were not included, and this specification helps to document
the understanding of each such assignment. In addition, such function
codes will be useful in counting some aspects of "before and after" when
frequencies are compared for particular purposes. The following
paragraphs describe the details of the function codes and the associated
SCAP analysis algorithms.

**Assignments Included in SCAP Analysis:**

Base station transmitter F = 3

Wireless link F = 4

Simulcast network F = 5

Trunked network F = 6

Single-message repeater network F = 7

Multiple-message repeater network F = 8

Mobile/mobile user net F = 9

US/USA/US&P incorporated into net F = 10

**Assignments not Included in SCAP Analysis:**

Obsoleted link F = 20.

Dedicated link F = 21

Receiver F = 22

Receive-only station F = 23

US/ USA/US&P w/o local F = 24

Low power (10 mW or less) F = 25

Mobile/portable-only networks F = 26

The function codes 3 through 10 describe GMF assignments for
transmitters that directly provide communication services to mobile
users, which services could be provided by a single shared network.
Since these function codes represent assignments that will be included
in the SCAP analysis, all of these function codes will also require a
network number "N."

**Base Station Transmitter (F=3).** This function code is used for an
individual base station serving a number of mobile users, where it is
likely that future service to these users could be provided by some type
of large shared radio system. Each individual base station transmitter
can be considered as an independent network and computed separately. All
locations on the PSC map with predicted coverage will be labeled with a
"1," which shows that one radio link is available at that particular
location. The ASC map is generated by counting the total number of
points on the map with coverage, setting K equal to that number of
points, and placing the value 1/K at all points that get coverage from
the base station. N = 0 is the recommended network value for a single
assignment, indicating that no other transmitters are part of that
network.

If base station transmitters at multiple sites use the same frequencies,
it may be difficult to know whether the base station signals can be
considered to be independent or not. In general, if the base stations
have coverage areas that overlap, they cannot be considered independent
and need to be analyzed as a multi-site network. A user in an
overlapping coverage area cannot receive multiple independent signals,
since the signals are transmitted at the same frequency and they will
interfere with each other. In the case of multiple same-frequency base
stations, the function code (F=3) can be used with multiple assignments
that all have an identical non-zero value for N. If the base station
coverage areas do not overlap, this network algorithm will give the same
results as multiple independent base stations.

The PSC map for the above network of multiple base stations can be
computed by finding all locations where a signal can be received from
one or more sites and placing a "1" in those locations. Locations
receiving signals from one base station (non-overlapping coverage areas)
would obviously get a PSC of "1." Locations receiving signals from more
than one base station (overlapping coverage areas) would also get a "1,"
because no more than one signal could be received without interference
(since all signals are at the same frequency). Therefore, the PSC maps
would have a "1" in each coverage location, no matter whether coverage
was from one base station site or from many sites. This result is
identical to that obtained from multiple simulcast sites. This
calculation might err on the side of being too optimistic, because many
locations receiving multiple signals would actually be able to receive
no signals; interference between the signals would prevent any signal
from being received. In addition, some multi-site systems may allow only
one site to transmit at one time to prevent interference between signals
radiated from multiple sites.

The ASC map for a multiple sites network can be calculated in the
following manner:

1\. Calculate the ASC maps for all base station sites individually,
using the same calculations as for a single base station.

2\. Combine the ASC maps for the individual base station sites as
follows:

> a\. At all locations where there is coverage only on a single ASC map,
> directly transfer the ASC values to the combined network ASC map.
>
> b\. For any locations where there is overlapping coverage, calculate
> an average ASC value from all of the non-zero ASC values at each
> location.

The above procedure should be used in any circumstances where multiple
base stations using the same frequencies might have overlapping
coverage. This algorithm will give the same ASC map results for multiple
non-overlapping base stations sites as when the sites are analyzed
individually and their individual SC maps are added together. This same
algorithm will be used to analyze multiple site repeater systems using
the same frequencies.

**Fixed Wireless Link (F=4).** This assignment is used for certain types
of fixed radio systems (i.e., stationary base station and mobile/fixed
auxiliary sites), whose services could be provided by some type of large
shared radio system. In general, a more complex model would need to be
used if the auxiliary sites communicate directly with each other,
instead of only communicating with the base station. Each individual
base station transmitter can be considered as an independent network and
computed separately. All locations on the PSC map with predicted
coverage will be labeled with a "1," which shows that one radio link is
available at that particular location. The ASC map is generated by
counting the total number of points with coverage equal to K and placing
the value 1/K at all points that get coverage from the base station. N =
0 is the recommended network value.

If this system is not suitable to be incorporated into a larger shared
system, it should be coded "F = 21." The difference between placing an
assignment into the category of "dedicated link" (F = 21) or "wireless
link" (F = 4) is whether the link function is able to be efficiently
provided by the future shared system. For example, a dedicated link
might be used to provide a narrowband backup voice and data link between
two federal communication centers; this link could not be practically
integrated into a future system. Another link might gather continuous
status/location data from a fleet of vehicles (all vehicles updated
every 30 seconds). While this could theoretically be serviced by a
future mobile system with digital messaging capabilities, via the mobile
radios in the vehicles, it would probably not be an efficient way to
provide the service, and more detailed analysis might eliminate it from
being a candidate for inclusion in the future network. However, a
nominally similar service providing river flood warning data (e.g.,
short data message every 15 minutes) might turn out to better match the
digital messaging capabilities in the future system; this system could
be a candidate for inclusion. Depending on the exact function of the
link and the features chosen for the future system, a given assignment
may be placed in either of these categories.

**Simulcast Network (F=5).** This function code identifies an assignment
used as part of a simulcast network, with multiple sites using the same
transmit frequencies and receive frequencies. A previously unused
non-zero value of "N" should be selected and used to label all simulcast
transmitters belonging to this network and operating on a given
frequency. The coverage areas from all base station transmitters at a
given frequency are calculated, and a total coverage area for the entire
set of transmitters is calculated. The PSC map is generated by putting a
"1" at all locations that receive coverage from one or more sites. The
ASC map is generated by counting the total number of points with
coverage equal to K and placing the value 1/K at all points that get
coverage from one or more base stations. Note that coverage at a single
point from multiple simulcast base stations only results in a PSC value
equal to 1 because the multiple base stations are all transmitting the
same signal. Therefore, only one signal can be received, irrespective of
how many base stations can deliver that single signal to the user.

In general, most simulcast networks use multiple frequencies. In this
case, all sites operating at a specific single frequency should be
calculated as a single network, with separate networks used for each
different frequency. If desired, SC maps can be developed for the total
simulcast system by combining the PSC maps and ASC maps for each
frequency (i.e., independently computed networks) belonging to the
simulcast system.

[]{.mark}

**Trunked Network (F=6).** This function code describes an assignment
that is used for a trunked network, using only local channels. In the
case of trunked networks, all channels at all base stations operate
independently; this is much different from the earlier simulcast
example. Therefore, a given trunked base station with ten channels would
provide ten possible independent signals at each point of coverage.
Coverage at a given location from two base stations (one with ten
channels and one with five channels) would provide the possibility of
receiving 15 independent signals.

Trunked networks should be assigned a function code (6, N), where N is
the same for all assignments (transmitter frequencies) at all base
stations in the entire trunked network. The peak SC map is constructed
by computing a coverage area for each transmitter and placing a "1" at
each location where coverage is available from that transmitter. The PSC
values are additive at a given location; coverage at a given location by
"M" different transmitters gives a PSC value equal to M for that
location. The ASC map is computed by calculating a coverage area for
each transmitter and counting the number of locations where coverage is
available equal to K. A value of 1/K is placed into the average SC map
at each location where coverage from that transmitter is available. The
ASC values are additive at a given location. Coverage at a given
location by M different transmitters (T~1~, T~2~, \... , T~M~ ) gives an
ASC value equal to 1/K~1~ + 1/K~2~ + \... + 1/K~M~ at that location,
where the K's are the coverage areas for the respective transmitters. In
general, all of the K's will be equal for transmitters at a given site,
but each different site will have different coverage areas.

One pair of frequencies at each site will be used for a control channel,
and it would therefore not be available to carry traffic. However, some
trunking technologies allow the control channel to carry traffic.
Moreover, trunked radio channels generally carry more traffic than
non-trunked channels. Therefore, all trunked system channels were
counted as traffic channels.

**Repeater Network (F=7).** This function code is used for a repeater
transmitter, or for a multi-site repeater network. If the repeater
network uses a standard pair of repeater frequencies at multiple
repeater sites with overlapping coverage areas to extend the
geographical coverage of a system of repeaters, the analysis of the
repeater system may need some additional detailed study, because it is
not usually immediately evident which combinations of the repeaters
could be used to support individual messages and which could not. The
multi-site analysis presumes the most efficient possible repeater
configuration; in some cases, the repeater network may only allow a
single message to be carried throughout the entire system. The
difference between these cases might also depend on options selected by
the user for the specific message.

**Single-Message Repeater Systems (F=7).** This function code designates
a repeater assignment, where the repeater (or repeaters) allows only a
single message to be carried on the repeater system. Repeater systems
are often constructed with multiple repeater sites with overlapping
coverage areas that all use the same receiver frequency and transmitter
frequency. This means that a mobile user could simultaneously transmit
to multiple repeaters, which would each repeat (transmit) the same
repeated message at the same frequency. Under such circumstances, the
multiple repeated messages could be expected to interfere with each
other, in the same way that interference can be caused if simulcast
transmitters are not carefully designed and adjusted. Designing such
repeater systems so that multiple repeaters do not transmit
simultaneously at the same frequency often prevents this interference.
Depending on how this is accomplished, a repeater system may (or may
not) carry multiple independent messages. F = 7 includes all
single-signal repeater systems. This includes systems that consist of a
single repeater site. Other included repeater systems use multiple
repeater sites that are controlled (e.g., with CTCSS codes) so that only
a single repeater site re-transmits a message at a given time. Zone
repeaters use multiple frequencies to transmit a single message from
multiple sites that provide an extended coverage area; however, all
sites transmit the same message content.

PSC maps for a single-message repeater system are computed by placing a
"1" at each location where there is coverage from one or more repeater
transmitters. ASC maps are computed by counting the total number of
locations with coverage from one or more sites equal to K and placing
the value 1/K at each location with coverage. Note that these
calculations are identical to simulcast systems.

**Multiple-Message Repeater Systems (F=8).** This function code
designates a multi-site repeater system that allows multiple independent
signals to be repeated. Although some repeater systems are designed so
that only a single message can be repeated at a given time, other types
of repeater systems can handle multiple simultaneous messages. For
example, consider a multi-site repeater system covering a large
geographical area. When mobile User A is using a specific site to relay
a message, an adjacent site (with approximately the same coverage area)
cannot simultaneously be accessed by mobile user B, since A and B would
be simultaneously using the same frequency at the same time in the same
geographical area. However, simultaneous use would be possible if User A
and User B were accessing repeater sites that were sufficiently
separated from each other so that User A's signal did not interfere with
User B's signal at the site which user A was attempting to access (and
vice versa). In this example, mobile users can operate independently
(using separate messages) in some geographical areas, but not in other
areas. This is the circumstance that function code (F = 8) is intended
to analyze. In addition, some repeater systems are designed to allow the
user to choose how the repeater system operates (e.g., perhaps passing a
message down a string of repeaters to headquarters or choosing to repeat
the signal on the local repeater). Such systems will also be designated
with F = 8, although F = 7 would appear to be correct for part of the
time.

[]{.mark}

The PSC map is calculated by finding the total coverage area of all base
station repeater transmitters and placing a "1" at all locations with
coverage.

The ASC map for the multiple sites can be calculated in the following
manner:

> 1\. Calculate the ASC maps for all repeater sites individually, using
> the same calculations as for a single repeater station.
>
> 2\. Combine the ASC maps for the individual repeater sites as follows:
>
> a\. At all locations where there is coverage only on a single ASC map,
> directly transfer the ASC values to the combined ASC map.
>
> b\. For any location where there is overlapping coverages, calculate
> an average value from all of the non-zero ASCs at each location.

The above procedure should be used in any circumstances where apparently
independent repeater sites using the same frequencies might have
overlapping coverage areas. If there is no overlap, this algorithm will
give the same results as calculating the SC maps for independent
repeaters and combining them.

**Mobile/Portable User Net (F=9).** This designation is used with an
all-mobile/portable user net having no fixed base stations. In general,
it may be difficult to determine the coverage area of such a system
according to a set formula. A location and radius may be indicated on
the assignment, or other data may become available. However, such a
system could obviously be served by a shared, trunked network, assuming
that the network provided service in the applicable system service area.

**US/USA/US&P Assignment (F=10).** This designation is used for a US/USA
/US&P assignment added into the shared network. Since such an assignment
has no localized geographical location and therefore no SC coverage
area, these assignments will need to be estimated individually by hand,
with some reasonable equivalent coverage included. For this reason, this
function code was not incorporated into the study.

The function codes 20-26 represent assignments that have not been
included in the SCAP analysis. This is because the codes represent
assignments whose functions are never included (e.g., receivers), or
because the function provided by a specific system could apparently not
be easily incorporated in a shared radio system. In the case of these
function codes, it is not necessary to include any value for N.

**Obsoleted Assignment (F = 20).** This indicates that the assignment
would no longer be needed if an integrated trunked network were
operational. Typical examples may include telemetry links used to
control or indicate the status of equipment associated with the present
LMR systems, or links used to transport communications between base
station sites (as an alternative to a wire line connection). The
important distinction is that such a link is not intended to directly
provide communications to users. This function designation indicates
that this assignment will not need to be supported in any way in the new
system. Note that F = 20 does not imply in any way that the assignment
is not needed to provide services to current networks, but only that its
specific function would not be specifically transferred to a comparable
network, especially when the actual architecture of an alternative
comparable future system has not yet been defined.

**Non-Incorporated Assignment (F=21).** This assignment is used for a
dedicated or special-purpose function that would not be expected to be
incorporated in, or replaced by, the future shared trunked radio system.
It is assumed that these frequency assignments will continue to be
needed whether or not a new trunked system is constructed. However, for
fixed links that intermittently transmit data or status in a geographic
area served by the shared system, future incorporation into the shared
system might be considered on an individual basis at a later time.

Since these links will be unaffected by any conversion to a future
shared trunked systems, F = 21 will be the initial default setting for
all assignments. If F = 21, the SCAP analysis program will ignore this
assignment.

**Receivers (F=22 or F=23).** The first round of SCAP analysis will
consider only transmitter assignments. It is assumed that many agency
transmitter assignments have matching receiver information. If the
receiver frequency is for a standard base station receiver or mobile
receivers paired with a transmitter at that same site, let F = 22. This
indicates that the specifics of the situation are adequately described
by the transmitter coverage and no further action is necessary on the
assignment. In many cases, however, the receiver information may provide
important non-standard information on the nature of the functions of the
associated network. Receive-only site information may identify
functional requirements to provide in-building coverage to handheld
transmitters, etc. If the receiver assignment is for a receive-only site
or for some other specialized receiver site, let F = 23. Initially, only
the transmitter information will be directly incorporated into the
geographical SC maps, but F = 23 will serve as a reminder for possible
later analysis that there are some special receiver requirements that
may need to be accounted for in the final design. Note that the practice
of providing assignments for receivers is optional and varies greatly
between agencies. These assignments will be ignored in the SCAP
analysis.

**US/ USA/ US&P Assignments (F=24).** The analysis assumes that any US/
USA/ US&P, and similar wide-area assignments having "000000\" latitude
or longitude values will be not be used to support any permanent local
radio infrastructure. Although the same frequencies identified by these
wide-area assignment types are often available for temporary or
permanent local uses, it is understood that any local permanent uses of
these frequencies will be identified by separate local assignments with
geographical coordinates and specifics. These local assignments for any
local use should be examined independently and designated with the
appropriate function codes. However, in this analysis of existing local
infrastructure capabilities, all US, USA, and US&P assignments that are
not specifically associated with a location and function will be
identified with F=24 and ignored in the SCAP analysis.

**Low Power Assignments (power = 10 mW or less) (F = 25).** This
includes any low power assignments (10 mW). An example of this category
is about 900 low power assignments for tracking wildlife tags used by
the Department of Interior and some wireless microphones used by
multiple agencies. These assignments will be ignored in the SCAP
analysis.

**Mobile/portable-only Assignments (F = 26).** This includes assignments
that include no specific base stations, but involve only portable or
mobile radios talking between each other. Typical applications might
involve a guard force patrolling a federal building, using handheld
radios to talk with each other. These were excluded from further
analysis, since they are using no fixed infrastructure that could be
replaced by a shared radio system. At some time in the future, it might
be useful to migrate such systems to become mobile units on a shared
system, but such a determination would be uncertain and premature at
this time. Therefore, the presumption is that such systems would
continue to operate in their present mode.

###### COMBINING SIGNAL CAPACITY MAPS

The PSC and ASC maps for each network can be generated by the SCAP,
after function codes have been assigned to each GMF assignment. The
resulting ASC and PSC maps can be combined with other ASC and PSC maps
to get ASC and PSC maps for any desired combination of transmitter
networks. The process of combining these SC maps is limited only by the
assumption that the original network SC maps were calculated in a
compatible manner--i.e., the same distance scales, the same technical
criteria for a definition of "coverage," etc. As long as these criteria
are maintained, SC maps could be combined from different frequency
bands, from different agencies, from various federal, state, and local
governments, etc. Attempts to combine SC maps from different services
might be possible, but one would need to carefully explore whether a
common meaning of "coverage" could be established for the different
services. The actual SC maps selected to be combined will be dependent
on the selection of combinations of agencies whose combined systems one
would seek to describe.

Page A-16/Blank

[^1]: National Telecommunications and Information Administration, U.S.
    Department of Commerce, *Manual of Regulations and Procedures for
    Federal Radio Frequency Management*, (May 2003 Ed.) (Revisions
    through January 2004), \[hereinafter NTIA Manual\], Chapter 1.

[^2]: Telecommunications Authorization Act of 1992 Act, 47 U.S.C.
    §§901-904 (2004) \[hereinafter NTIA Act\].

[^3]: NTIA Manual, *supra* note 1, at part 2.3.3.

[^4]: ^.^

[^5]: *Id., at* part 2.1.

[^6]: NTIA Act, *supra* note 2, 47 U.S.C. at 903 (d)(3).

[^7]: ^.^

[^8]: National Telecommunications and Information Administration, U.S.
    Department of Commerce, NTIA Report 93-300*, Land Mobile Spectrum
    Efficiency: A Plan for Federal Government Agencies to use More
    Spectrum-Efficient Technologies* (October 1993) \[hereinafter NTIA
    Report 93-300\].

[^9]: Institute for Telecommunication Sciences, National
    Telecommunications and Information Administration, U.S. Department
    of Commerce, NTIA Report 94-311, *A Survey of Relative Spectrum
    Efficiency of Mobile Voice Communication Systems* (July 1994).

[^10]: The second phase of this study is on-going.

[^11]: National Telecommunications and Information Administration, U.S.
    Department of Commerce, NTIA Special Publication 01-48, *Alternative
    Frequencies for Use by Public Safety Systems: Response to Title
    XVII, Section 1705 or the National Defense Authorization Act for FY
    2001* (December 2001), \[Hereinafter NTIA Special Publication
    01-48\], at 2-5.

[^12]: The spectrum assignments that were utilized by the agencies prior
    to their transition to the DHS, were, for the most part, reassigned
    to the DHS. See, Pub. L. No. 107-296 (2002).

[^13]: ^?^ *See* *supra* note 9, at 3-1.

[^14]: The GMF is the federal government's master list of frequency
    assignments authorized by NTIA, but does not necessarily represent
    the number of pieces of radio equipment associated with each
    assignment. There may be many pieces of radio equipment associated
    with a single frequency assignment. In addition, the GMF utilized
    for this study does not contain any classified federal frequency
    assignments**.**

[^15]: These station classes are defined in the NTIA Manual, *supra*
    note 1, at 6-18.

[^16]: Area assignments are: US&P (United States and Possessions), US
    (the 50 states and the District of Columbia), and USA (the 48
    contiguous states and the District of Columbia).

[^17]: See *supra* note 13.

[^18]: *See supra* note 13.

[^19]: U.S. Department of Agriculture, *Mission of USDA Agencies and
    Offices*, at http://www.usda.gov/mission/miss-toc.htm.

[^20]: Federal public safety agencies have engaged in a long‑term
    standards development process known as P25/TIA 102, a collective
    effort by industry and the state and local public safety agencies.
    This effort has resulted in the development of an extensive set of
    standards for digital public safety wireless communications.

[^21]: U.S. Department of Commerce, *The Commerce Mission Statement*, at
    http://www.osec.doc.gov/bmi/budget/strtgc/aintro.pdf.

[^22]: U.S. Coast Guard, *Overview*, at http://www.uscg.mil/overview/.

[^23]: NTIA has identified 40 (20-VHF and 20-UHF) interoperability
    channels in the 162-174 MHz and 406.1-420 MHz bands for law
    enforcement and incident response plans. *See* NTIA Manual, *supra*
    note 1, at Section 4.3.16.

[^24]: U.S. Department of Defense*,* *DOD 101: An Introductory Overview
    of the Department of Defense*, at http://www.dod.mil/pubs/dod101/.

[^25]: *See*, Section 5 for a more detailed description of this system.

[^26]: U.S. Department of Energy, *About* *DOE*, at http://www.doe.gov

[^27]: *See* Federal Aviation Administration*, What We Do-Mission,* at
    http://www.faa.gov

[^28]: See *supra* note 10.

[^29]: U.S. Department of Homeland Security, *DHS Organization,* at
    <http://www.dhs.gov/dhspublic/theme_home1.jsp>.

[^30]: *Id.,* at <http://www.dhs.gov/dhspublic/display>? Content = 3345.

[^31]: U.S. Department of the Interior*, DOI Quick Facts,* at
    http://www.doiu.nbc.gov/orientation/facts.cfm.

[^32]: U.S. Department of Justice, *Organization, Mission, and Functions
    Manual, March 2004, Overview*, at
    [http://www.usdoj.gov/jmd/mps/manual/overview.htm](http://www.usdoj.gov/jmd/______/manual/overview.htm)

[^33]: U.S. Department of Justice and U.S. Department of the Treasury,
    *High Level Design Report* (on file with author).

[^34]: U.S. Department of the Treasury, *Duties and Functions* at
    [http://www.ustreas.gov/education/duties/](http://www.ustreas.ov/education/duties/)

[^35]: ^?^ With the establishment of the Department of Homeland Security
    in 2002, the U.S. Secret Service and their functions, transferred
    from the Department of the Treasury effective March 1, 2003. *See*
    *supra* note 10.

[^36]: ^?^ NTIA Special Publication 01-48, *supra* note 9 at 3-2.

[^37]: United States Postal Service, *Five Year Strategic Plan --
    Introduction* (2003), at
    [http://www.usps.com/strategicdirection/\_\_pdf/fiveyearplan2004-2008.pdf](http://www.usps.com/strategicdirection/__pdf/fiveyearplan2004-2005.pdf)

[^38]: U.S. Department of Veterans Affairs, *About VA.,* at
    http://www1.va.gov/about_va/.

[^39]: Formerly the Federal Specialized Mobile Radio (FEDSMR); *see*
    Section 5 for a detailed description.

[^40]: NTIA Act, *supra* note 2.

[^41]: NTIA Report 93-300, *supra* note 6, at 1.

[^42]: *Id.,* at 8.

[^43]: After Jan. 1, 2005, all systems in the 162-174 MHz band must
    conform to this standard. After Jan. 1, 2008, all systems in the
    406.1-420 MHz band must conform to this standard.

[^44]: NTIA Manual, Section 5.3.5.2. B, s*upra note* 1, at 5-24-26.

[^45]: Federal Communications Commission, ET Docket No 03-65,
    *Interference Immunity Performance Specifications for Radio
    Receivers*, March 24, 2003. 18 F.C.C.R. 6039 (2003).

[^46]: National Telecommunications and Information Administration, U.S.
    Department of Commerce, *Comments of the National Telecommunications
    and Information Administration in the matter of* *Interference
    Immunity Performance Specifications for Radio Receivers,* ET Docket
    No 03-65, November 12, 2003.

[^47]: The standards are published in the Telecommunications Industry
    Association/Electronics Industries, an American Standards Institute
    (ANSI) accredited process. For example, *see*, http://www.ANSI.org.

[^48]: National Telecommunications and Information Administration*,
    Notice, Spectrum Management and Policy Summit, 67 Fed. Reg. 10,682
    (* March 5, 2002). *See also*, NTIA Spectrum Summit at
    http://www.ntia.doc.gov/ntiahome/summit/index.html.

[^49]: ^d^

[^50]: *Spectrum Policy Task Force Report*, ET Docket No. 02-135,
    Federal Communications Commission, (November 15, 2002), at 21,
    available at
    http://hraunfoss.fcc.gov/edocs_public/attachmatch/doc_228542A.pdf.

[^51]: ^?^ *Id.*, at 21

[^52]: ^t^

[^53]: *Telecommunications: Better Coordination and Enhanced
    Accountability Needed to Improve Spectrum Management*, General
    Accounting Office, GAO-02-906, (September 2002), at 25.

[^54]: *Id.,* at 31.

[^55]: ^t^

[^56]: General Accounting Office, *Telecommunications: History and
    Current Issues Related to Radio Spectrum Management, testimony
    before the Committee on Commerce, Science, and Transportation,* U.S.
    *Senate*, GAO-02-814T (June 11, 2002), at 1.

[^57]: *Id., at 14.*

[^58]: *Memorandum on the Spectrum Policy for the 21^st^ Century*, 39
    Pub. Papers 23 (June 9, 2003).

[^59]: *Id*.

[^60]: National Telecommunications and Information Administration,
    Docket No. 040127027-4027-01,*\
    69 Fed. Reg. 4,923* (February 2, 2004), available at
    http://www.ntia.doc.gov/ntiahome/frnotices/2004/spectruminitiativenoi_01282004.pdf.

[^61]: Spectrum Policy for the 21st Century- The President's Spectrum
    Policy Initiative: Report 1 "Recommendations of the Federal
    Government Spectrum Task Force, U.S. Department of Commerce, NTIA,
    June 2004; Spectrum Policy for the 21st Century- The President's
    Spectrum Policy Initiative: Report 2 "Recommendations for State and
    Local Governments and Private Sector Responses, U.S. Department of
    Commerce, NTIA, June 2004.

[^62]: *Departments of Commerce, Justice, and State, the Judiciary, and
    Related Agencies Appropriations bill, Fiscal Year 1999, H.R. Rep.
    No. 105-636,* at 12 (July 20, 1998).

[^63]: *See* Appendix A, at A-2, for a detailed explanation of the
    threshold and confidence/reliability criteria.

[^64]: National Telecommunications and Information Administration, U.S.
    Department of Commerce, NTIA Report 82-100, *A Guide to the Use of
    the ITS Irregular Terrain Model in the Area Prediction Mode* (April
    1982).