CBO

A

S T U D Y

The Army’s Bandwidth Bottleneck

August 2003

The Congress of the United States # Congressional Budget Office 
Notes

Unless otherwise indicated, all dollar amounts are fiscal year 2003 dollars.

The top photo on the cover is by Marni McEntee of the European Stars and Stripes (©2003 by

Stars and Stripes). The bottom photo is courtesy of the U.S. Army.
Preface

Over the past decade, the U.S. Army’s principal modernization initiative has been its

digitization effort, designed to harness the power of the microchip to significantly improve the

fighting capabilities of soldiers on the battlefield. But implementing that initiative presents

significant challenges. Digitization requires the rapid transmission of large amounts of

information over significant distances. Experiments conducted to date as well as recent operations

in Iraq, where troops employed some of the results of the service’s digitization efforts, have shown

that that requirement is difficult to fulfill not only under battlefield conditions but also in more

benign circumstances. Since 1999, the focus of the Army’s modernization program has shifted

to what it terms transformation—making its forces deployable more quickly while maintaining

or improving their lethality and survivability. Although digitization is no longer the Army’s

primary modernization initiative, it remains a key element of transformation.

In the past several years, questions about the size of the information flow associated with

digitization and the communications bandwidth to support it—that is, the capacity to move

information at sufficient speeds—have spurred the Army to adopt several large radio and network

communications programs. Ultimately to cost tens of billions of dollars, those programs are

currently planned to provide initial operational capability by about 2010.

This Congressional Budget Office (CBO) study, which was prepared for the Subcommittee on

Tactical Air and Land Forces of the House Committee on Armed Services, examines the issue

of how much bandwidth will be required to achieve the goal of digitization (the bandwidth

demand) versus how much bandwidth will be provided by the Army’s planned communications

programs (the bandwidth supply). CBO finds that significant shortfalls currently exist for the

Army in the supply of bandwidth. Moreover, under the service’s current plans, demand will

continue to exceed supply beyond 2010—after the Army begins fielding its next generation of

advanced radios and other communications equipment. The study examines several options that

would improve the future match between bandwidth supply and demand. However, in keeping

with CBO’s mandate to provide impartial analysis, this report makes no recommendations. 

Paul Rehmus of CBO’s National Security Division wrote the study under the general supervision

of J. Michael Gilmore. Army Cadet Kevin Linzey provided substantial assistance in the analysis

of bandwidth for unmanned aerial vehicles. At CBO, Barbara Edwards, David Moore, and David

Newman reviewed early drafts and provided helpful comments. Numerous U.S. Army officers

also contributed useful comments on and data for drafts of the report as well as the underlying

analysis. The author would like to cite in particular the support of Lt. Col. Charles Gabrielson,

Col. Edward Cardon, and former Chief of Staff of the Army Erik Shinseki.
iv THE ARMY’S BANDWIDTH BOTTLENECK

Leah Mazade edited the study, and John Skeen proofread it. Cindy Cleveland produced drafts

of the manuscript and tables. Christian Spoor, assisted by Sharon Corbin-Jallow, prepared the

study for publication, and Annette Kalicki produced the electronic versions for CBO’s Web site.

Douglas Holtz-Eakin

Director

August 2003

This study and other CBO publications

are available at CBO’s Web site:

www.cbo.gov
1

2

3

CONTENTS

Summary ix

Bandwidth Supply and Demand in Today’s Army 1

Background on the Army’s Digitization Initiative 4

Bandwidth Supply at Army Commands Today 5

Bandwidth Demand at Army Commands Today 8

Comparing Bandwidth Supply and Demand in 2003 12

Operation Iraqi Freedom 14

Bandwidth Supply and Demand in 2010 19

Bandwidth Supply at Army Commands in 2010 19

Bandwidth Demand at Army Commands in 2010 20

Comparing Bandwidth Supply and Demand in 2010 23

Mitigating Mismatches Between Bandwidth Supply

and Demand 25

Buy Better Radios in Greater Quantities 25

Reallocate Currently Planned Spending 27

Reduce Demand and Better Manage 

Persisting Mismatches 28

Appendixes

The Army’s Current Communications Initiatives 31

Extrapolating Continuous-Flow Information Across

Command Levels 37

Compressing Data to Reduce Bandwidth Demand 43

Glossary of Abbreviations 45
vi THE ARMY’S BANDWIDTH BOTTLENECK

Tables

S-1. Effective Bandwidth Supply Versus Peak Demand in 2003, by

Command Level x

S-2. Effective Bandwidth Supply Versus Peak Demand in 2010, by

Command Level xii

1. Maximum Engineering and Effective Bandwidth for Typical

Army Communications Equipment in 2003 8

2. Number and Types of Radios Available at the Ops Nodes in Digitized 

Units During Peak Operations in 2003, by Command Level 10

3. Maximum Effective Bandwidth Available to Army Operations

Networks in 2003, by Command Level 11

4. Peak Demand for Continuous-Flow Bandwidth in the Digitized

Division’s Operations Net in 2003 11

5. Peak Demand for Continuous-Flow Bandwidth in 2003, by 

Command Level 12

6. File Sizes of Episodic Throughputs in Army Ops Channels in 2003, 

by Type of Throughput and Command Level 13

7. Equivalent Peak Continuous-Flow Bandwidth for Episodic

Throughputs in 2003, by Throughput Type and Command Level 14

8. Total Peak Demand for Effective Bandwidth in 2003, by

Command Level 15

9. Effective Bandwidth Supply Versus Peak Demand in 2003, by

Command Level 16

10. Effective Bandwidth Available to Army Operations Networks

in 2010, by Command Level 20

11. Number of Operating UAV Systems, by Command Level 21

12. Peak Effective Bandwidth Demand in 2010 Under Two

Assumptions About TUAVs, by Command Level 22

13. Effective Bandwidth Supply Versus Peak Demand in 2010,

by Command Level 23
CONTENTS vii

A-1. Planned Investment in the Joint Tactical Radio System, by

Organization and Cluster 33

A-2. Effective Bandwidth Supply Versus Peak Demand in 2010,

with a JTRS Substitute 35

B-1. Peak Bandwidth Demand at the Digitized Division, Brigade,

and Battalion Levels in 2003, by Mission 38

B-2. Peak Bandwidth Demand for the Operations Nets at the Digitized

Division, Brigade, and Battalion Levels in 2003, by Source of Demand 39

B-3. Effective Bandwidth Supply Versus Peak Demand in 2003

Using a Factor-of-Two Extrapolation, by Command Level 40

B-4. Effective Bandwidth Supply Versus Peak Demand in 2010

Using a Factor-of-Four Extrapolation, by Command Level 41

Figures

S-1. The Army’s Bandwidth Bottleneck xi

1. Notional Throughput Capacity per Node 26

2. Total Projected Investment in Ops Net Equipment, by 

Command Level 27

3. Cost of the Capacity Provided per Ops Net, by Command

Level 27

4. Cost of the Capacity Utilized per Ops Net, by Command

Level 28

Boxes

1. Information Technology: Some Concepts and Definitions 2

2. The Evolving Mix of Wired and Wireless Battlefield 

Communications 6

3. Operational Versus Theoretical Bandwidth 9

Summary

Bandwidth is a term used in much of the telecommunications industry as a measure, usually expressed

in bits per second, of the rate at which information moves

from one electronic device to another. To the extent that

people are aware of bandwidth issues in everyday life, they

most often confront them in the form of a shortfall in

bandwidth—awaiting retrieval of an (Internet) Web page

over phone lines and modems that are too slow, for

example, or being told on Mother’s day to phone again

later because no telephone lines are available.

Bandwidth is a central issue for any communications

system. The U.S. Army’s current battlefield communications system still largely reflects the days when the pressing need was for verbal messages that relied on battlefield

telephones. The expectation that a phone system would

suffice changed in 1991, when then Army Chief of Staff

Gordon Sullivan began the service’s digitization initiative.

The initiative’s goals were to significantly increase Army

units’ knowledge, in real time, of the disposition and

combat capabilities of both friendly and enemy forces,

thereby providing commanders with a common operational perspective, and to improve their ability to command and control their forces by speeding up the delivery

of information. General Sullivan’s vision was to exploit

the ever-increasing speeds of the microchip—which, in

practice, meant introducing onto the battlefield unprecedented quantities of computers, communications equipment, and software. 

An explosive demand for bandwidth accompanied the

initiative. Underlying it was an expectation of responsiveness—that information would be transmitted quickly.

The (often unarticulated) model was the increasingly fast

Internet service that the civil telecommunications

industry was providing. For the most part, the demand

for bandwidth in homes and offices was met in the mid1980s and early 1990s by what was at the time redundant

telephone capacity predominantly through copper wires,

which had accumulated over almost 100 years. As that

capacity was exhausted in the 1990s, the telecommunications industry increased the available bandwidth by laying

thousands of miles of fiber-optic cable—a solution that,

for the most part, is not available to Army troops on the

move during battle.

Some personnel in the Army recognized that the bandwidth provided by the battlefield telephone system would

be inadequate to support the goals of digitization. Nonetheless, the service did not fully realize the challenge that

implementing digitization would pose to both its communications community and the wireless telecommunications industry in general. In particular, the Army did not

know the size of its total requirement for bandwidth and

had not considered the substantial difference in cost

between using fiber-optic cable and using radios to satisfy

that demand. (For an equal amount of bandwidth, cable

is currently about 25 to 50 times cheaper.)

After a decade of effort, the Army’s digitization initiative

has fallen short of its goals;1

 the service’s plans now focus

1. The Army planned as recently as 1999 to bring digitization to

47 brigades (32 active and 15 reserve) by 2009. As of now, however, it has abandoned its intention to digitize more than a twodivision corps plus its support elements and is now focusing on

digitization of the interim portions (the Stryker brigades) of the

transformed Army’s future Objective Force. The new goal is to

digitize 13 units equivalent to brigades by 2009.
x THE ARMY’S BANDWIDTH BOTTLENECK

on transformation, although digitization still remains an

objective, albeit a subsumed one. (Transformation aims

for significantly lighter and more easily deployable units

that nevertheless have increased lethality and survivability

compared with units today.) Consequently, the Army

continues to invest significant amounts of money in new

communications bandwidth to support its revised goals

for digitization as well as new programs associated with

transformation. The latter category includes the planned

widespread use of unmanned aerial vehicles (UAVs),

whose operation requires large amounts of bandwidth.

In this study, the Congressional Budget Office (CBO)

analyzes the current and future total demand for communications bandwidth to support operations officers at

all levels of command within the Army. CBO then

compares that demand with the total bandwidth supplied

by communications systems in place today and those

planned for the future. Although numerous studies of

Army communications bandwidth have been conducted,

none has attempted to assess total demand and supply at

all levels of command.

CBO’s analysis is intentionally conservative insofar as it

attempts, when there is doubt, to assess both future communications capabilities as being greater than they might

be and future bandwidth demand as being less than it

might be. Therefore, in cases in which CBO projects that

future demand appears to exceed supply, this study may

underreport the degree of mismatch.

CBO’s analysis has yielded the following conclusions

regarding the bandwidth available to operations officers.

First, at all levels of command within the Army, the

current demand for bandwidth is larger than the

supply—shortfalls of as much as an order of magnitude

(or up to 10 times the amount of supply) can exist. Second, shortfalls in the supply of bandwidth will persist at

some command levels through and after 2010, when the

capabilities associated with the Army’s transformation

begin to be put into the field. Thus, after what is now

planned as an investment of approximately $20 billion

in new communications equipment, the Army will fall

short of its goals at certain command levels by an order

of magnitude. (Unless otherwise indicated, all dollars are

fiscal year 2003 dollars.)

Bandwidth Supply and Demand

in Today’s Army

At various Army headquarters in the field—for example,

at the corps, brigade, or division levels of command—

there are multiple communications networks. This analysis focuses on networks that serve the operations officers,

denoted the ops desks or ops nets. Other communications

networks (often located in the same command centers)

are not unimportant, but in many cases they have similar

equipment and are used to transmit similar amounts of

information. (Examples of other communications networks are the intelligence and fire-support nets, which

serve, respectively, intelligence personnel and personnel

in the headquarters who control attacks on targets.)

Summary Table 1.

Effective Bandwidth Supply

Versus Peak Demand in 2003,

by Command Level 

Command

Levela

Relative Supply

Versus Peak

Demand (S : D)b

Corps 1 : 1 to 4

Division 1 : 5 to 8

Brigadec 1 : 1.5 to 38

1 : 20 to 309

Battalion 1 : 10 to 20

Company 1 : 2 to 6

Platoon 1 : 0.5 to 2

Squad/Vehicle 1 : 2 to 6

Source: Congressional Budget Office.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and firesupport) become less clear.

b. Based on an approximate logarithmic scale, the color coding is as follows: yellow indicates that supply is between about one-third and three

times demand (a marginal supply/demand match); light orange signifies

that demand is approximately three times supply, and orange, that demand is between three and 10 times supply. Red (used here for the

lower brigade-level relationship and at the battalion level) means that

demand exceeds supply by a factor of 10 or more.

c. The up-arrow (8) indicates the throughput (bandwidth) rate for communications to equivalent or higher command levels. The down-arrow

(9) indicates the throughput rate to lower command levels.
SUMMARY xi

Summary Figure 1.

The Army’s Bandwidth Bottleneck 

Source: Congressional Budget Office.

Therefore, CBO’s analysis of bandwidth supply and demand for the ops nets may illuminate supply/demand

mismatches occurring in the Army’s other communications networks.

Expressing the supply of bandwidth at each command

level as one, Summary Table 1 displays the current relationship between supply and demand. Ranges are used

for peak demand because only rough estimates of it are

available. (The Army’s data on peak bandwidth demand

are a limited collection of experimental observations,

test results, and simulations that have not all been obtained in consistent, controlled environments. In view

of those limitations, CBO has reviewed its use of the

available data with communications experts throughout

the Army.) CBO’s analysis focuses on peak demand because, with rare exceptions, it corresponds to the most

intense battlefield activity, when failure is least tolerable.

The color coding in the table indicates how well the

estimates of bandwidth supply and demand match. At

no level of command is there a significant excess of supply relative to demand. If supply and demand are

within a factor of about three (based on an approximate

logarithmic scale), yellow is used to express caution.

Caution is warranted for two reasons: modest delays in

transmission are likely, with unknown effects on operations; and there is little potential to accommodate additional growth in demand.

The colors light orange, orange, and red indicate worsening degrees of mismatch. Light orange and orange

correspond to increasingly long delays in message

transmission or lost messages. Red—used in Summary

Table 1 for the mismatch at the brigade level indicated

by the down-arrow and the mismatch at the battalion

level—means that demand exceeds supply by factors of

10 or more, resulting in severe operational effects.

Computer memories, file systems, and network file

servers overfill and sometimes “crash”; the network, or

parts of it, fail; and command and control becomes

“analog” as soldiers abandon the digital system and

return to voice-only communications. (See Summary

Figure 1 for a simplified depiction of the mismatch

between bandwidth supply and demand that currently

exists at different levels of command.)

The reversion to analog command and control is an

outcome reported both officially and unofficially in

many of the Army’s advanced warfighting experiments

(AWEs) that were conducted between 1998 and 2001.

The recent war in Iraq, by comparison, saw troops

adopting a different approach. The Army provided

them with a limited version of digitized communica-
xii THE ARMY’S BANDWIDTH BOTTLENECK

tions (which nevertheless included the new capability of

graphical displays of cumulative data), and units handled bandwidth shortfalls by using character-based

transmissions (which are similar to ones from the terminal teletypes of an earlier era). Those messages were

transmitted using e-mail and “chat room” formats (like

those available over the Internet), which demand relatively little bandwidth.

Bandwidth Supply and Demand

in 2010

Within the decade, both the supply of and demand for

bandwidth on the battlefield are expected to increase

substantially with the fielding of components of the

next-generation Army. Key among them are the first

units to be outfitted with the Future Combat System

family of vehicles, the Shadow UAV, and a large

amount of new communications equipment. The programs now generating that equipment are major elements of the Objective Force, the Army’s current name

for the lighter, more deployable force that it expects to

have in place in 2010.

Advances in communications equipment that the Army

plans to field include the Joint Tactical Radio System

(JTRS), Warfighter Information Network-Tactical

(WIN-T), and Multiband Integrated Satellite Terminal

(MIST). The WIN-T and MIST are major components

of the Army’s plans to improve communications between the brigade, division, and corps command levels

(known as the upper tactical Internet). The JTRS is the

primary advance anticipated in communications between the brigade command level and smaller units

(known as the lower tactical Internet). A number of features differentiate the two Internets; an important one is

that the upper tactical Internet is augmented with satellite communications, whereas the lower is not. 

In addition to the new communications equipment, the

Army is considering a change in the internal architecture of its communications networks, which by 2010

would redistribute the information that those networks

carry. A plan being discussed for the Objective Force

would load all non-UAV information from the operations, intelligence, and fire-support networks onto a

single “backbone net” and divert all UAV data to a separate high-capacity network.

By 2010, as Summary Table 2 shows, the most severe

mismatch between supply and demand will have moved

Summary Table 2.

Effective Bandwidth Supply

Versus Peak Demand in 2010,

by Command Level

Command

Levela

Relative Supply

Versus Peak

Demand (S : D)b

Corpsc 1 : 10 to 30

Divisionc 1 : 10 to 30

Brigadec,d 1 : 3 to 108

1 : 5 to 159

Battalion 1 : 1.5 to 3

Company 1 to 4 : 1

Platoon 4 to 10 : 1

Squad/Vehicle 7 to 20 : 1

Source: Congressional Budget Office.

Note: The range in relative demand at the brigade and higher levels of command is associated with either the proposed “backbone” architecture

or the case in which the current architecture is maintained and

downlinks from unmanned aerial vehicles are heavily networked. (See

Chapter 2 for details.)

a. At the higher command levels, the table refers to the operations networks

only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and fire-support)

become less clear.

b. Based on an approximate logarithmic scale, the color coding is as follows: green (used here at the platoon and squad/vehicle command levels) means that supply exceeds demand by approximately a factor of

three or more. Yellow indicates that supply is between about one-third

and three times demand (a marginal supply/demand match), and orange

signifies that demand is approximately three to 10 times supply. Red

(used here for the corps and division levels) means that demand exceeds

supply by a factor of 10 or more.

c. If the architecture for information distribution located in the tactical

operations centers at these command levels is altered, as the Army is

considering doing, then operations officers will share information in a

new "backbone net." In that case, the upper end of the projected range

of bandwidth demand would apply.

d. The up-arrow (8) indicates the throughput (bandwidth) rate for communications to equivalent or higher command levels. The down-arrow

(9) indicates the throughput rate to lower command levels.
SUMMARY xiii

from the brigade level to the corps and division levels

(shown in red on the table). That shift occurs because

the JTRS, if it works as planned, will significantly increase the supply of bandwidth relative to demand in

the lower tactical Internet. Further, at the lowest command levels, the JTRS will provide some capacity to accommodate additional growth in demand beyond 2010.

At the higher command levels, however, the increase in

the supply of bandwidth attributable to the WIN-T and

the MIST will be swamped by substantial increases in

demand, CBO projects. As a result, the new backbone

nets, if implemented, will experience bottlenecks at the

corps and division levels that are quantitatively similar

to those existing at the battalion and brigade levels today.

Options to Mitigate 

Mismatches Between 

Bandwidth Supply and Demand

CBO examined several options to either improve the

future match between bandwidth supply and demand

or lessen the risk that the mismatch will be significant.

Its analysis considered three general approaches: boosting the amount of bandwidth above the increases already envisioned in the Army’s programs, reducing the

demand for bandwidth, and better managing the mismatch between supply and demand.

CBO chose not to develop alternatives that would increase the supply of bandwidth after it analyzed two

such approaches: funding efforts to develop new technology that would mature by 2010 or buying more of

the currently planned systems. The technology approach is probably not feasible because the Army’s

planned new communications programs are already

adopting all current and projected advances in technology. An approach that increases capacity by purchasing

more equipment is also problematic. For example, some

Army experts have suggested that projected bandwidth

demand can be met by purchasing 20 times more sets of

WIN-T equipment than the service is now planning to

buy. However, current cost estimates for the WIN-T

program already range between $4 billion and $9 billion, and additional spending of that magnitude may

simply be an unlikely prospect.

The three alternatives described below suggest ways to

eliminate lower-priority demand for bandwidth and

better manage the demand that remains. The first two

alternatives would stop the transmission of information

that might be of lesser priority yet would be expected to

contribute significantly to the future mismatch between

bandwidth supply and demand at some command levels. The third would mandate the adoption of software

tools, some of which are starting to become commercially available, that could allow better management of

the demand for bandwidth when it exceeded supply.

# Eliminate video teleconferencing, and in its place

substitute teleconferencing plus a whiteboard capability.

# Do not network UAV “downlinks.” Maintain the

autonomous sensor-to-shooter links (video downlinks from the UAVs), but do not transmit the

video signals that they produce throughout the

command structure, as the Army has planned. (Under this option, UAV video feeds would be sent directly to a single fire-support or intelligence center

but would not be transmitted farther.) 

# Mandate that automated bandwidth management

tools, which dynamically constrain the use of bandwidth and are now coming onto the commercial

market, be built into the software that is expected to

underlie both the upper and lower tactical Internets

in 2010. The earliest such tools focus on network

software; by implementing them and later extending them to applications software, the Army could

manage future bandwidth shortfalls as they occurred and mitigate their effects.

1

Bandwidth Supply and Demand

in Today’s Army

The Office of the Joint Chiefs of Staff has asserted,

in its 2001 publication Joint Vision 2020, that “[i]nformation, information processing, and communications networks are at the core of every military activity.” In response to that guidance, the Army is seeking to create an

information technology (IT) environment in which computers are routine battlefield tools, information (measured

in bits per second) passes continuously over wired and

wireless channels, and the complex communications

infrastructure necessary to keep all of that gear operating

is in place. This Congressional Budget Office (CBO) study

focuses primarily on how the Army transmits streams of

information, known as bandwidth, and how much

information it wants to transmit, both now and in the

future. (Box 1 defines and discusses several IT terms and

concepts.) In particular, the study addresses mismatches

between the amount of bandwidth demanded at various

command levels and the amount of bandwidth supplied.

The Army faces a number of problems in implementing

its IT strategy on the battlefield. The service needs much

more bandwidth than it has available today to support

both its current systems and those planned for the future,

but the cost of additional bandwidth is high. Moreover,

as this study concludes, the Army’s planned investments

in communications capability will not fulfill its projected

future requirements. Those conclusions have been echoed

in numerous discussions that CBO has conducted with

members of the Army’s IT community as well as in eight

recent studies on various aspects of the service’s demand

for bandwidth.1

 None of those studies, however, has

attempted to systematically assess the Army’s total band1. Monica Farah Stapleton and Yosry Barsoum, “C4ISR Systems

Engineering Analyses and Modeling & Simulation” (briefing

prepared for the Army Communications and Electronics Research,

Development, and Engineering Center by AMSAA [Army Materiel

Systems Analysis Activity] and the Mitre Corporation, September

9, 2002); J.L. Burbank and others, “Concepts for the Employment

of Satellite Communications in the Army Objective Force” (draft,

Johns Hopkins University Applied Physics Laboratory, August

2002); RAND Arroyo Center, “Future Army Bandwidth

Needs—Interim Assessment” (briefing prepared for the G6/Army

Chief Information Officer, July 10, 2002); Yosry Barsoum,

“Bandwidth Analysis (ACUS Only) of Division Main, Maneuver

Brigade TOC, and Tank Battalion” (briefing materials prepared

for the Army’s Communications and Electronics Command by

the Mitre Corporation, February 29, 2000); Steve Chizmar and

others, “Digitization at Brigade and Below (DB2) Study” (briefing

prepared for the Army Materiel Systems Analysis Activity, Aberdeen

Proving Ground, Maryland, December 1, 1999); Army Medical

Department Center and School, “Medical Force Digitization

Overview” (briefing prepared for the Deputy Chief of Staff for

Command, Control, Communications, and Computers, January

1999). The following were provided to CBO by the staff group

of the Army Chief of Staff: Army Signal Center and Fort Gordon,

Directorate of Combat Developments, Modeling and Simulation

Branch, Architecture Division, First Digitized Forces System

Architecture (1DFSA): Version 2.02, Simulation Analysis/Study,

White Paper (main text and attachment titled “Satellite Communications Capacity Study,” June 30, 1999; released to CBO

on May 14, 2002); and Lt. Gen. P. Cuviello, “Projected Bandwidth

Usage and Capacity” (briefing prepared for the Army Chief of Staff

by the G6/Army Chief Information Officer, August 2002; released

to CBO on January 14, 2003).

CHAPTER
2 THE ARMY’S BANDWIDTH BOTTLENECK

Box 1.

Information Technology: Some Concepts and Definitions 

To allow a better understanding of the analysis and

conclusions presented in this Congressional Budget

Office (CBO) study, some common terms and concepts

from this technical field are discussed below.

Measuring Information Flow

The rate of flow of information is usually expressed in

bits per second, a bit being the smallest representation

of information in a binary code of zero or one. A shorter

phrase for bits per second is bandwidth, as defined in

the applied communications industry.1

 This report uses

bandwidth synonymously with the term throughput.

The more bits per second that an information flow

contains, the higher the bandwidth. Convenient units

for bandwidth today are typically kilobits per second

(thousands of bits per second, or Kbps), megabits per

second (millions of bits per second, or Mbps), or

gigabits per second (Gbps), which is a thousand times

more. Most communications equipment today operates

at rates ranging from a few kilobits per second to one

or more gigabits per second.

 

Voice Transmission Rates. For the spoken word, actual

information content flows at hundreds to a few thousands of bits per second. For example, the phrase

“There’s a fire in the room out back” is usually spoken

in about a second. That is, in a second, 35 characters,

each represented by eight bits of information (in the

ASCII code, for instance), or some 280 total bits, are

1. That definition of bandwidth is not the one used in scientific

fields or in much of the engineering community. There,

bandwidth is defined as the difference between two frequencies

(radio frequencies, for instance) rather than bits per second.

However, the two definitions can be functionally related and

are nearly proportional at low noise levels. Thus, communications specialists often shift back and forth, without confusion,

between the two definitions in different technical contexts.

communicated. Very rapid speakers, such as auctioneers,

might convey 3,000 bits of information per second.

When voices are transmitted over a phone system today,

much more than just the core information is conveyed;

the transmission also includes tone, volume, timbre,

and other nuances that distinguish one voice from

another. After a century of engineering, the number of

those additional context bits per bit of core information

is about 10 times more. Consequently, commercial

phone systems do not operate at 3 Kbps but are instead

usually rated at a minimum of 32 Kbps per phone line.

The Army standard is somewhat lower—16 Kbps per

phone line—but is essentially as satisfactory for most

users.

Data Transmission Rates. Although people who talk on

the phone are content with the level of communications

provided by 32 Kbps of bandwidth, they demand much

higher throughputs when using their home computers

on the Internet. Today, many people who access the

Internet over a phone line use a 56 Kbps modem. (A

modem is a device that converts signals produced by,

say, a computer to a form compatible with, for example,

a telephone.) Fifteen years ago, a typical speed for a

modem was 1,200 bits per second. As modem speeds

began doubling, and doubling again, 56 Kbps was the

first modem speed that took full advantage of the rated

throughputs of standard phone lines and telephone

interfaces—as well as nearly accommodating the first

level of improvement above 56 Kbps, which is usually

64 Kbps.2

 (Faster speeds require alternative technology,

2. The actual throughput of a typical copper point-to-point commercial phone line varies and depends not only on commercial

switching rates but on the quality of the telephone as well.

Although most phone lines are conservatively rated at 32 Kbps,

they can operate easily at 64 Kbps when they have been

equipped with higher-quality interfaces.
CHAPTER ONE BANDWIDTH SUPPLY AND DEMAND IN TODAY’S ARMY 3

Box 1.

Continued 

such as a digital subscriber line, or DSL, or a cable

system that bypasses the phone system’s copper wires.)

Video Transmission Rates. As was the case with the

above analysis of phone lines, it is relatively simple to

crudely estimate the size of the bandwidth required for

transmitting video images. The typical computer screen

today is about 1,000 pixels across by 1,000 pixels high.

(Pixels are the small, individually modifiable elements

of a video screen.) Basic color representation requires

a minimum of eight bits of information per pixel. The

cinematic illusion of movement requires about 32

frames per second.3

In addition, just as the phone system requires an extra

order of magnitude of bandwidth for the context bits,

so, too, computer systems require context bits in about

the same 10-to-1 ratio. (The context bits in video

transmissions, however, handle such features as noise,

packet switching, error correction, and retransmission.)

Therefore, if no adjustments were made, the bandwidth

required for a single continuous video transmission

(sometimes called streaming video) would be about

2,560 Mbps [2,560 bps = (1,000 x 1,000 pixels/frame)

x (8 bits/pixel) x (32 frames/second) x (10 context

bits/bit)].

Fortunately, modern engineering practices reduce that

information load by about a factor of 100 by applying

data compression and so-called delta techniques.4

3. Some observers notice “jumpiness,” or monitor flicker, if the

speed of motion is much less than that. Commercial standards

today are usually better, or about 60 frames per second.

4. Delta techniques are a set of algorithms for determining those

portions of the new frame that are different from the last frame.

Once determined, only those different portions are transmitted.

Moreover, trimming the number of pixels in the frame

slightly and the frames per second somewhat can reduce

the load further, by a factor of 10. Therefore, with a

penalty of only a slight loss in resolution and an increase

in flickering, 2,560 Mbps can be reduced to a

bandwidth load of just a few megabits per second, which

is typical for a single point-to-point video transmission.

Software Layers

In a computer network, the software necessary for its

operation is sometimes differentiated into layers, and

measurements of information bandwidth differ from

layer to layer. An e-mail system is an example of

applications-layer software. If an output—that is, an

e-mail—is to be sent to another user across a large network, the outputs of the e-mail software must be

augmented by information from local operating systems,

network software, and numerous other software layers.

If at some stage in the transmission a radio is employed,

more software (the data link and physical layers) is

needed at the lowest network layers to transmit bits over

an antenna, monitor whether the bits are transmitted

without interference, and initiate retransmissions if

errors occur. A higher level of bandwidth is required

at the data link and physical layers than the level needed

to support a throughput at the applications layer.

This Congressional Budget Office study distinguishes

between the two levels. Bandwidth associated with

the data link and physical layers (the throughput that

is often cited by hardware manufacturers) is called

engineering bandwidth; bandwidth at the applications

layer is referred to as effective, or operational, bandwidth. Specifically, CBO’s analysis compares the demand for and supply of effective (or operational)

bandwidth for the Army’s point-to-point communications, because that level of throughput is what personnel observe in the field.
4 THE ARMY’S BANDWIDTH BOTTLENECK

width requirements by communications network and

command level.

In this study, CBO analyzes the current and future total

demand for communications bandwidth to support operations officers at all tactical levels of command (from the

corps down to the individual squad or vehicle) within the

Army. The analysis then compares that demand with the

total bandwidth supplied by the service’s current and

planned communications systems. This chapter considers

bandwidth supply and demand today; Chapter 2 estimates

supply and demand in 2010. Chapter 3 discusses several

options for addressing the bandwidth supply/demand gap

that exists today and is expected to persist—although at

a different point in the command structure—in the future.

Background on the Army’s 

Digitization Initiative

The Army’s battlefield communications system was

originally designed to handle voice and character-based

(old-fashioned terminal teletype) messages. In general,

those types of communications, whose upper limit on rate

of flow is several kilobits per second, require relatively little

bandwidth. To send 100 poor- to average-quality voice

messages simultaneously, therefore, requires bandwidth

in the range of several hundred kilobits per second. Rates

for character-based information are similar. The difference

between several and several hundred kilobits per second

generally defines the range in bandwidth, or throughput,

of the tactical radios that the Army employs today on the

battlefield. (Certain augmentations to that equipment were

fielded during the recent Iraq war and constitute

exceptions to that statement. They are discussed at the end

of the chapter.) Using mobile retransmission towers

(relays) around the battlefield and the current generation

of satellite communications, the Army can meet its current

needs for bandwidth for voice and character-based

communications.

To transmit computer data and video signals, however,

requires much more throughput. Such transmissions on

today’s battlefields and those of the future include video

“downlinks” from unmanned aerial vehicles (UAVs),

computer displays of data depicting battlefield situations,

video teleconferencing, and telemedicine, in which doctors

examine wounds and advise on treatment remotely. Much

of the bandwidth demand reflected in those examples is

associated with streaming (continuous) video imaging,

which requires a minimum of several megabits per second

of throughput to be considered continuous by most

viewers.

If 100 video and data transmissions are to be supported

simultaneously—a typical scenario in a larger headquarters

such as for a division or corps, the demand for bandwidth

grows from several megabits per second to several hundred. That throughput is three orders of magnitude (10

x 10 x 10, or 1,000, times) greater than the Army’s current

communications system was originally designed to handle.

It is more than 10 times larger than the demand that the

system is projected to be able to handle in the future,

following the improvements that the Army is currently

planning.

The substantial increase in bandwidth demand on today’s

battlefield is due to the Army’s digitization initiative.

Begun in 1992 by then Army Chief of Staff General

Gordon Sullivan, the initiative was designed to field

advanced information technologies (computers, software,

databases, and communications equipment) to rapidly

provide “situation awareness” and support for decisionmaking. The phrase situation awareness denotes knowing

the locations of both U.S. forces (in military terms,

referred to as Blue situation awareness) and enemy troops

(known as Red situation awareness). Within a short time,

Army leaders had also identified the subsidiary goals of

fielding a first digitized division by 2000 and a first

digitized corps by 2004, with the rest of the Army to

follow.

The digitization of the Army has proceeded more slowly

than was originally anticipated. As recently as 1999, the

Army was planning to have 47 digitized brigades (32 active

and 15 reserve) in the field by 2009. However, when planning began in 1999 for the new Objective Force of the

future (following the installment of General Eric Shinseki

as Army Chief of Staff), the idea of carrying digitization

beyond the first digitized corps was abandoned and

supplanted by new goals for the “transformed” army,

which incorporated the objectives of digitization as a

subset. (The Army’s transformation involves making forces

deployable more quickly while maintaining or improving

their lethality and survivability.)
CHAPTER ONE BANDWIDTH SUPPLY AND DEMAND IN TODAY’S ARMY 5

Under the umbrella of the Objective Force, the number

of brigades to be digitized by 2009 has been reduced to

13—seven maneuver brigades in the first digitized corps

and six new Stryker brigades. (Stryker brigades are interim

units whose organization and capabilities place them

between traditional brigades and Objective Force units.)

By the end of 2003, the Army plans to have five digitized

brigades. Four will be components of the 4th Infantry

Division and 1st Cavalry Division in the first digitized

corps, and the fifth will be the first Stryker brigade. 

Bandwidth Supply at Army 

Commands Today

To understand how the Army intends to manage the

communications networks and equipment that it now has

—and the bandwidth they provide—one must consider

how the hardware being used and the information

coursing through it are handled within the Army’s tactical

command structure. The model of that structure used by

CBO in its analysis is the structure of the first digitized

division (the 4th Infantry Division) and the first digitized

corps (the Third Corps). By adopting the Army’s recent

digitization framework, or architecture, as its starting

point, CBO’s analysis follows the Army’s current IT

strategy fairly closely, noting anticipated future changes

in architecture as appropriate. In addition, while battlefield

situations involve both wired and wireless (sometimes

referred to as radio frequency) communications, this study

focuses more on wireless messaging, because of its dominance in mobile battlefield operations and its relative cost.

(Box 2 gives some sense of the interplay between the two

types of messaging on the battlefield.)

In the digitized Army, radios are organized into communications networks. As a shorthand, the networks are often

referred to, synonymously, as nets or nodes. Army nets can

be differentiated by the combat mission (operations, intelligence, logistics, fire support, and so on) that they predominantly serve. They are also characterized by the types

of radios that produce their transmissions and by the other

nets with which they directly communicate.

For instance, the operations officer in a battalion will

manage communications from the operations net, usually

designated the “ops” net. Today, the radios that this officer

typically uses include an NTDR (Near-Term Data Radio),

an EPLRS (Enhanced Position Location Reporting

System), and one or more SINCGARSs (Single-Channel

Ground and Airborne Radio Systems). At the battalion

level, the operations officer (or a subordinate) directs large

volumes of information to operations officers in the

companies below and in the brigade above; takes orders

and assessments from the brigade; and receives and

transmits situation assessments from other operations

officers in adjacent battalions.

Lesser volumes of information also pass to the ops net

from the intelligence, fire-support, and other networks.2

When such nets are colocated in the same command

center, communications between them pass over a wired

network, usually a local area network (LAN).3

 When nets

are not colocated, which is common for communications

between different levels of command or between forward

and main headquarters, information from the intelligence,

fire-support, and other nets that must be shared places

additional demands on the ops net’s wireless bandwidth.

(Table 1 on page 8 presents the equipment—mostly radios

—that is now found in the operations nets of digitized

Army units. The new and improved radios and other

equipment that the Army plans to develop and field by

the end of the decade are discussed in Chapter 2.)

The effective communications bandwidth provided by

the Army’s voice and data radios is typically reduced below

the maximum (engineering) rates by a factor of about 10,

owing to the bandwidth needed for context bits and

channelization (see Box 3 on page 9). Because the mobile

subscriber exchange, or MSE (the equivalent of a private

telephone system), has a much higher degree of channelization than any of the other radios, its throughput is

reduced by roughly a factor of 100 for point-to-point

transmissions. 

The operations officer at a given level of command has

one or more radios, or “pipes,” available for communica2. Those networks carry information internal to their mission areas

and analogous in size to the large volumes passing through ops

channels.

3. A LAN is one example of a network that is “wired,” or connected,

by very high bandwidth fiber-optic cable.
6 THE ARMY’S BANDWIDTH BOTTLENECK

Box 2.

The Evolving Mix of Wired and Wireless Battlefield Communications

Traditionally, battlefield communications systems have

used radios (wireless communications), and very high

bandwidth messaging made possible through the use

of fiber-optic cable (wired communications) has been

nonexistent. Wired communications using copper wires

have long existed only in or near tactical operations

centers (TOCs), with the principal purpose of tying

together its local phone system. With such a system,

the Army fought Desert Storm, and it faced no significant restrictions on its operations because of shortfalls

in bandwidth.

In that conflict, the pace of the throughputs that radios

provided for the command-and-control system (including what were then considered high-capacity satellite

communications) was satisfactory because nearly all

messages represented analog voice traffic for which the

equipment and procedures were designed. U.S. forces

were able to communicate much more freely than their

adversaries could, and U.S. commanders’ decisionmaking cycle was much faster as well. By the time of

the war in Afghanistan, special forces personnel were

using military variants of (wireless) cell phones to

transmit voice and simple numerical data, such as global

positioning system coordinates, to Air Force and Navy

bombers.

In some battlefield situations in which the Army

requires very high levels of bandwidth, it is available.

Specifically, in combat environments where distances

between operations centers are short, the nodes (in this

instance, a group of colocated nets) move infrequently

or not at all, and the risks of direct enemy attack are

negligible, large demands for bandwidth are easily

handled. In those circumstances, Army doctrine calls

for running high-bandwidth land lines in the form of

bundles of copper cable or using pulse-coded modulated

(PCM) lasers, or both, to communicate between nodes.

Also, within the TOCs of digitized units, fiber-optic

cable is routinely used to connect elements of the internal local area networks, or LANs.1

Both PCM lasers and LANs support megabit-per-second

throughput. But they are restricted in their geographic

extent and limited to fixed nodes. The transmission

range for a LAN is usually several hundred meters.2

PCM lasers are limited to about 20 kilometers because

of their susceptibility to beam drift caused by wind and

other atmospheric conditions. LANs and land lines

typically avoid that problem, but they can take several

hours to deploy. 

1. That kind of connection has been demonstrated within TOCs

associated with the 4th Infantry Division. Although in

principle, a variety of LAN architectures are possible, the

Army’s intra-TOC LANs are organized as 100 Mbps Ethernets.

(An Ethernet is a kind of LAN that is now recognized as an

industry standard.)

2. LAN geography is always limited, but the details depend on

the speed of light in the fiber, the minimum synchronized

operating frequencies of the nodes and other equipment on

the network, the network’s topology, and other physical

characteristics.

tions (see Table 2 on page 10). The approximate capacity

of what is termed a trunk line at a particular command

level (essentially, the operations network) can be obtained

by adding up the capacities provided by the available

individual pipes.4

Combining the information in Tables 1 and 2, CBO

estimated the maximum total effective throughput that

the Army’s ops nets can provide. To do that, CBO made

several assumptions (which represent ideal circumstances):

for a given point-to-point communication, the throughput

load can be fitted to perfectly match the maximum oper4. If the demand for information through those pipes could be exactly

matched to their size, then the trunk line’s capacity would exactly

equal the sum of the pipes’ bandwidths. In practice, however, that

does not always occur; therefore, the sum represents an upper

bound on the trunk line’s actual bandwidth. The trunk line for

digital communications does not include a number of older,

generally analog radios that carry relatively little message traffic.
CHAPTER ONE BANDWIDTH SUPPLY AND DEMAND IN TODAY’S ARMY 7

Box 2.

Continued

In addition to those communications techniques, the

Army’s operational headquarters in Korea, Saudi Arabia,

and Europe were linked within the past decade to the

Pentagon and other U.S.-based headquarters using fiberoptic-based international commercial networks. Often

called wide-area networks (WANs), they have become

highly redundant in much of the world during the past

10 years. From a practical standpoint, however, WANs

are restricted to fixed nodes.

Such approaches (WANs, LANs, PCM lasers, or

bundled land lines) are generally of high bandwidth,

but they are not practical for mobile vehicles and are

therefore inappropriate for maneuvering forces that

operate over wide areas. They are also less useful in cases

in which a given message has a large intended audience

or the precise locations of the recipients are unknown.

In such instances, traditional (wireless) radios are ideal.

They operate in broadcast mode, sending their signals

out widely, and are useful for all levels of forces.

Consequently, wireless, in spite of its lower intrinsic

bandwidth relative to wired communications, and its

much higher cost (25 to 50 times more) per unit of

throughput, is the most practical communications

medium for troops.

To supply its deployable forces, the Army has fielded

hundreds of thousands of radios. The number of nodes

that must in principle be linked by wireless technology

to support an army on the move is about 100,000. To

provide largely voice communications, the Army’s

inventory of radios in the field numbers about 220,000,

or enough to support two major theater wars simultaneously.3

Wireless technology can reach the megabits-per-second

range, and the Army currently has several programs

designed to bring that rate of bandwidth to the

individual soldier. The problem is that such highbandwidth radios, designed to operate both on their

own and with existing radios, may cost about $127,000

apiece.4

 The minimum investment required to replace

the entire fielded inventory of radios with new models

is thus about $28 billion. In addition, because those

replacement radios are still in development, that

estimate of their cost is subject to a number of risks

(discussed later), some of which could increase the

investment substantially.

3. The figure 220,000 is also approximately the number of fielded

radios capable of digital communications. In addition, the

Army fields tens of thousands of older, mostly voice-only

radios. However, the Congressional Budget Office has generally

ignored those radios in its analysis because they are not part

of the battlefield Internet and their contribution to overall

communications bandwidth is small and decreasing.

4. That average cost was noted in the December 2002 Selected

Acquisition Report for the Joint Tactical Radio System,

Cluster 1. The average unit procurement cost including

research and development spending exceeds $140,000.

ational capabilities of the available radios; input and output throughputs are equal;5

 and all intended recipients

are within an average operational range of all the radios.

Under such assumptions, the data throughput rates of

individual radios can be added to estimate total throughput capability—the total bandwidth supply—provided

by the radios available in each ops net (see Table 3 on page

11).

As the table shows, the digitized brigade has two measures

of available bandwidth. That command level employs both

the Army’s beyond-line-of-sight (BLOS) satellite com5. For the most part, that assumption is valid for ops nets, which

according to Army doctrine share information with both higher

and lower command levels. For other nets, the assumption may

not apply. Fire-support nets, for example, often require much

higher bandwidth for inputs than for outputs because their incoming traffic is dominated by data from high-bandwidth sensors such

as UAVs, whereas their outgoing traffic is made up of relatively

low bandwidth messages telling troops to fire at specific targets.
8 THE ARMY’S BANDWIDTH BOTTLENECK

Table 1.

Maximum Engineering and Effective Bandwidth for Typical Army

Communications Equipment in 2003

(In kilobits per second)

Point-to-Point Data Throughputs

Radio/Communications

Equipmenta

Typical Battlefield

Command Levels

Maximum

Engineering Average Effectiveb

SINCGARS (SIP) Vehicle to Corps 16 1.7

EPLRS (VHSIC) Company to Corps 128 13.3

NTDR Company to Corps 288 30

Interface Standardc Battalion to Army 16 1.5 to 7

MSE Battalion to Corps 64 1.7

MSE with ATM Switch Brigade to Corps 2,048

d

5.1 to 6.7

DSCS-111/93 Division to Army 256 27e

DSCS-111/85 Division to Army 768 82e

SMART-T Brigade to Army 4,620 481e

STAR-Tf Corps to NCAg 24,000 2,500e

Source: Congressional Budget Office based on the Army’s 1999 budget hearing for its command, control, communications, and computer (C4) systems.

a. See the glossary of abbreviations on page 45.

b. These averages are lower than the maximum engineering throughputs because of the bandwidth required for context bits and channelization. The averages apply

until about 2007, when the Army will begin to field the initial examples of a new generation of communications equipment (see Chapter 2 and Appendix A for more

details). After a transition period between 2007 and 2010, Objective Force units in 2010 are scheduled to be the first units to incorporate the new equipment in

its entirety.

c. Used for multiplexers, modems, routers, switches, radio access units, and other equipment.

d. The maximum potential rate is 8.192 megabits per second using the (high-capacity line-of-sight) HCLOS radio—provided the interfaces are programmed to operate

at the higher rates and frequencies are available. However, at present, the interfaces are not so programmed.

e. Extrapolated from the reductions in bandwidth that occur for lower-frequency radios.

f. The termination in 2001 (for default, as a result of delays and cost overruns) of the ongoing contract for the STAR-T has cast doubt on the program’s future. To

fill the void produced by the termination, the Army is currently using commercially available systems of approximately the required throughputs and considering

replacement candidates. 

g. The NCA, or National Command Authority, refers to the command chain that extends to the Secretary of Defense and the President. 

munications and its line-of-sight (LOS) radio communications. The bandwidth provided by BLOS satellite

communications is several orders of magnitude greater

than that available to battlefield LOS radios. The brigade

can communicate with higher commands using the BLOS

transmitters, as signified by the up arrow. However, it

must talk to lower commands with LOS NTDRs,

indicated by the down-arrow, because digitized battalions

do not have satellite receivers. That satellite communications distinction also divides the upper tactical Internet

(which is available to commands at the brigade level and

above) from the lower tactical Internet (available to the

brigade and lower command levels).

Bandwidth Demand at Army 

Commands Today

Experiments have shown that message traffic and data that

provide situation awareness and support for decisionmaking, including digital telephone calls, are the bulk of

the information transmitted in the Army’s communications system. Communications traffic can be thought of

as either approximately continuous or approximately

episodic. In the former case, called continuous-flow information, bits per second is the relevant measure; in the

latter case, referred to here as episodic information, the size

of the message file (in bits) is the appropriate gauge. For

instance, situation assessments of U.S. forces that are
CHAPTER ONE BANDWIDTH SUPPLY AND DEMAND IN TODAY’S ARMY 9

Box 3.

Operational Versus Theoretical Bandwidth

Operational point-to-point throughputs are always significantly lower than their theoretical maximums. That reduction

stems from two factors: context bits and channelization.

Context Bits

For military radios, the requirement for context bits for digital

throughput is an amalgam of a number of elements. Most

of them are simply the result of trade-offs among the engineering constraints associated with hardware, software, and

waveforms. Conceptually, however, most of the reduction

in throughput attributable to context bits derives from the

following requirements and considerations:

# Network Management. The Army’s tactical Internet uses

standard commercial Internet formats such as http, TCP,

and IP.1

 Each format has a somewhat different overhead,

data-packing format, and packet-transmission protocol.

# Network Architecture. Particularly at higher headquarters

levels, a network’s performance in terms of throughput

depends on the network’s topology—the number of

nodes, the router configurations, the numbers and linkages of relays, and the degree to which messages are multicast (sent to multiple nodes simultaneously). In practice,

the network’s performance degrades as the number of

internal nodes, relays, and routers increases.

# Forward Error Correction and Retransmission. Overhead

(for example, parity bits), checksum generation, and the

time spent by the packet transmitter and receiver in

checking errors cut bandwidth even when error rates are

low. When error rates are high, message retransmissions

also reduce effective bandwidth. Forward error correction,

which in its simplest form involves parity bits and some

form of data redundancy, allows many errors to be fixed

without initiating retransmissions. However, when forward error correction fails, packet retransmissions may

1. Respectively, hypertext transfer protocol, transmission control

protocol, and Internet protocol. Each format is optimized

differently for different types of data.

be initiated by both the transmitter and the receiver.

Although often transparent to the communications

system’s user, packet retransmission requests and packet

retransmissions often dominate message traffic at longer

ranges where “noise” becomes a significant problem.

# Encryption and Decryption. Throughput can be slowed

if encryption/decryption devices do not operate fast

enough to deal with the message traffic.

# Frequency-Hopping Overhead. Radios can be designed to

randomly change the frequencies at which they are transmitting to make it harder to detect and jam transmitted

signals. The processing associated with frequency hopping

reduces effective throughput.

# Time-Hopping Overhead. Radios can be designed to randomly stagger their transmissions to make signal detection

and jamming more difficult. The processing associated

with those delays reduces effective throughput.

# Software Inefficiencies. Hardware devices and the software

that makes them function are designed according to certain assumptions about the communications network in

which they will operate and the rates of information flow

that will apply. As networks age (that is, become loaded

with more and newer devices), those assumptions about

the network configuration may become invalid, which

can lead to reduced throughput.

Channelization

Channelization is the term used to express the number of

different data flows a radio can simultaneously support.

Simpler radios like the Single-Channel Ground and Airborne

Radio System will support either one data channel or one

voice channel but not both at once. (The operator flips a

switch to use one or the other.) The mobile subscriber

exchange—the Army's digital phone system—can be manually

set to simultaneously handle large numbers of phone calls

(high channelization) or reconfigured to provide one higherbandwidth channel (low channelization). Low channelization

might be used to support a video teleconferencing transmission. The greater the channelization, the lower the effective

point-to-point throughput will be.
10 THE ARMY’S BANDWIDTH BOTTLENECK

Table 2.

Number and Types of Radios Available at the Ops Nodes in Digitized Units

During Peak Operations in 2003, by Command Level

Command

Levela

SINCGARS

Links

EPLRS

Links

NTDR

Links

Satellite

Links

Corps 1 1 1 1

Division 1 1 1 1

Brigade 1 1 1 1

Battalion 1 1 1 0

Company 1 1 0 0

Platoon 1 1 0 0

Squad/Vehicle 1 0 0 0

Source: Congressional Budget Office based on Department of the Army, Army Tactical Communications (1999), which details the architectural design of the digitized

Army.

Notes: In addition to the radios, or “pipes,” noted above, which form the trunk lines for the flow of digital information, operations officers may sometimes use analog

voice-only systems such as walkie-talkies or several types of purely analog radios. Those analog systems carry a communications load that is not significant

for CBO’s analysis.

The numbers represent the average number of pipes allocated to the operations officer. For instance, in the column labeled “Satellite Links,” a digitized brigade

command center usually has three independent satellite terminals (and satellites) available. However, during peak operational conditions, intelligence officers

and fire-support activities are typically using two of the terminals—leaving only one, on average, for the operations officer.

See the glossary for abbreviations.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for

example, operations, intelligence, and fire-support) become less clear.

arriving asynchronously every minute or so from a number

of points are best represented as a continuous flow of

information. By contrast, a command for a dynamic retasking (also known as a dynamic unit task order, or UTO)

may occur only once a day.6

Bandwidth Demand for Continuous-Flow Information

The Army has studied the impact of digitization on peak

continuous bandwidth demand at the division, brigade,

and battalion levels. (For details of that study, see Appendix B.) For continuous-flow information, the digitized

division generates a peak demand on the operations net

of between 2.5 Mbps and 4 Mbps. Major consumers of

bandwidth are ordinary telephone traffic, the Army Battle

Command System (ABCS), and video teleconferencing

(see Table 4).

7

 The ABCS is differentiated into segments

for classified and unclassified information.

Although data on bandwidth demand are available for the

brigade and battalion levels of command, similar data do

not exist for the other command levels. Nonetheless, peak

continuous demand for them can be extrapolated from

the data available for the three higher command levels.

The key assumption in the extrapolation is that infor6. A requirement for a dynamic retasking occurs when a unit is

“chopped” from one commander to another—for instance, when

a battalion that is subordinate to one brigade at the start of battle

is reassigned to another brigade during the course of an operation.

Many command and logistics responsibilities are severed and

reestablished in such a retasking, requiring the reconfiguration of

many network files (for example, address lists and control files).

7. The ABCS is a so-called system-of-systems created from the Army’s

Tactical Command and Control System (ATCCS) and the

Force XXI Battle Command, Brigade and Below (FBCB2)

program. The ATCCS is one of the original command-and-control

system-of-systems. Created in 1979, it serves as an organizational

umbrella for several Army command-and-control programs such

as the All Source Analysis System and the Army Field Artillery

Tactical Data System, which were initiated in 1969 to manage

intelligence and artillery data, respectively. FBCB2 is a system of

hardware, software, and databases providing automated capability

for situation awareness and command and control to brigade and

lower command levels.
CHAPTER ONE BANDWIDTH SUPPLY AND DEMAND IN TODAY’S ARMY 11

mation requirements change from command level to

command level in proportion to alterations in the span

of control over resources and personnel. Since resources

and personnel increase by roughly a factor of three at each

command level, so, too, will information requirements.

In its estimates of bandwidth demand for continuous-flow

data, therefore, CBO assumed that at the corps level, the

demand for bandwidth was three times the demand at the

division level and that each command below the battalion

level required one-third less bandwidth than the next

higher command.

That “factor-of-three” assumption has been analyzed both

in this study and by the Army (see Appendix B for details).

Data on information flows at several different levels of

command, although incomplete, were analyzed in one

of the Army studies surveyed for this report; the results

suggest that the actual scaling factor probably lies between

Table 3.

Maximum Effective Bandwidth

Available to Army Operations

Networks in 2003, by Command Level

(In kilobits per second)

Command

Levela

Total

Effective

Throughputb

Corps 2,550

Division 533

Brigadec 5338

379

Battalion 37

Company 15

Platoon 15

Squad/Vehicle 1.7

Source: Congressional Budget Office.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and firesupport) become less clear.

b. Point to point, under an assumption of perfect load balancing. In practice, throughput rates may be less.

c. The up-arrow (8) indicates the throughput rate for communications to

equivalent or higher command levels. The down-arrow (9) indicates the

throughput rate to lower command levels.

Table 4.

Peak Demand for Continuous-Flow 

Bandwidth in the Digitized Division’s

Operations Net in 2003 

(In kilobits per second)

Source of

Demand Size of Demand

Army Battle Command System

Classified, nonlogistics traffic 300 to 1,000

Unclassified, mostly logistics traffic 100 to 300

Telephone (Digital)a 1,400

Unmanned Aerial Vehicles 100 to 300

Video Teleconferencing 1,000

Source: Congressional Budget Office based on data from the Department

of the Army (see Appendix B for details).

a. Analog telephone communications employing a number of analog radio

and walkie-talkie systems are also used but are not considered in this

analysis because they are either independent of the communications

trunk lines or contribute little to throughput demand.

two and four.8 However, for the sake of specificity and

because the results of the analysis remain qualitatively

the same, CBO used a factor of three in its analysis.

(Table 5 presents the results of applying the factor-ofthree extrapolation to the data in Table 4.)

Bandwidth Demand for Episodic Data

Episodic transmissions on the battlefield fall into several categories: fragmentary orders (FRAGOs), operations orders (OPORDs), fused intelligence reports,

UTOs, and map resynchronizations.9

 As noted earlier,

8. Barsoum, “Bandwidth Analysis (ACUS Only).” The data and

analysis are discussed in Appendix B.

9. FRAGOs are usually short amendments to operational orders and

are transmitted as character data. OPORDs are rather lengthy

operational orders that are issued once or twice daily. They

comprise character-based information including force subordination, disposition of the enemy, the commander’s intent, operational

goals for the commander’s force elements, and decision branch

points. Fused intelligence reports are the intelligence summaries

produced by intelligence officers that are shared with operations

officers. Map resynchronizations, or “resyncs,” occur because

information associated with digital maps must be updated when

a unit moves from one map sector to another.
12 THE ARMY’S BANDWIDTH BOTTLENECK

Table 5.

Peak Demand for Continuous-Flow Bandwidth in 2003,

by Command Level

(In kilobits per second)

Army Battle Command System Updates

Command Levela Classified Unclassified

Digital

Telephone VTCb

UAV and Common

Sensorsb

Corps 1,000 to 3,000 300 to 1,000 4,000 1,000 100 to 300

Division 300 to 1,000 100 to 300 1,400 1,000 100 to 300

Brigade 100 to 300 30 to 100 300 300 100 to 300

Battalion 30 to100 n.a. 100 300c

100 to 300

Company 10 to 30 n.a. 30 n.a. n.a.

Platoon 3 to 10 n.a. 10 n.a. n.a.

Squad/Vehicle 1 to 3 n.a. 3 n.a. n.a.

Source: Congressional Budget Office based on data from the Department of the Army (see Appendix B for details).

Notes: The estimates of bandwidth demand in this table were calculated by applying a "factor-of-three" extrapolation to the data in Table 4.

UAV = unmanned aerial vehicle; n.a. = not applicable for that command level.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks

(for example, operations, intelligence, and fire-support) become less clear.

b. Video teleconferencing and UAVs have bandwidth requirements that are independent of command level. 

c. In the digitized battalion, collaborative planning, which is a component of the classified Army Battle Command System, and video teleconferencing are not in

operation simultaneously.

the relevant measure of such messages is the size of the

file being sent, which CBO estimated on the basis of

data gleaned from the advanced warfighting experiments (AWEs) held between 1998 and 2001 at the brigade and division levels and from subject matter experts

in communications. Collectively, those experts, who

were drawn mainly from the operations, C4 (command, control, communications, and computers), and

resources offices of Army headquarters, have experience

at multiple command levels generating and using such

types of episodic messages (see Table 6).

Calculating peak demand for continuous-flow data at

all command levels requires an estimate of the average

frequency with which episodic throughputs occur. But

no such data have been collected. Therefore, CBO has

again generated assumptions, based on information

from Army subject matter experts, about such frequencies. FRAGOs and fused intelligence reports are assumed to arrive once a minute at commands below the

brigade level and once an hour at commands above it.

OPORDS, UTOs, and map resychronizations are assumed not to occur during peak operations.

Using those assumptions, CBO calculated the equivalent peak continuous information flow associated with

those episodic transmissions. Bandwidth demand for

those messages, CBO estimates, would be significant

only at the lowest levels of command (see Table 7 on

page 14). CBO then combined the estimates for both

continuous-flow and episodic transmissions to yield an

estimate of total continuous bandwidth demand at each

command level (see Table 8 on page 15).

Comparing Bandwidth Supply 

and Demand in 2003

CBO compared the maximum effective bandwidth

available at the operations desks of various tactical command levels (shown in Table 3) with its estimates of

total demand at those levels (from Table 8). The results

of CBO’s comparison show that at no command level

is there currently a substantial excess of supply relative
CHAPTER ONE BANDWIDTH SUPPLY AND DEMAND IN TODAY’S ARMY 13

Table 6.

File Sizes of Episodic Throughputs in Army Ops Channels in 2003, by Type of

Throughput and Command Level

(In kilobits)

Command Levela

Fragmentary

Ordersb

Operational

Ordersc

Fused

Intelligence

Reports

Unit Task

Orders Map Resyncsd

Corps 100 10,000 100 1,000 3,000 to 10,000

Division 100 1,000 10 to 100 1,000 1,000 to 3,000

Brigade 10 100 10 to 100 1,000 300 to 1,000

Battalion 1 10 10 to 100 1,000 100 to 300

Company 1 10 10 to 100 100 30 to 100

Platoon 1 10 10 to 100 100 10 to 30

Squad/Vehicle 1 10 10 to 100 100 3 to 10

Source: Congressional Budget Office based on data from Army subject matter experts and from the advanced warfighting experiments held between 1998 and

2001 at the brigade and division levels.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks

(for example, operations, intelligence, and fire-support) become less clear.

b. Usually short amendments to operational orders, which are transmitted as character data.

c. Issued once or twice daily, operational orders comprise character-based information including force subordination, disposition of the enemy, the commander’s

intent, operational goals for the commander’s force elements, and decision branch points.

d. Map resynchronizations, or “resyncs,” occur because information associated with digital maps must be updated when a unit moves from one map sector to

another.

to demand. In the worst case (for communications

from the brigade to lower command levels), demand

exceeds supply by an order of magnitude or more (that

is, by more than 10 to one). In the best case (at the platoon level), demand is somewhere between one-half

and twice the bandwidth supply.

To strengthen the qualitative aspects of CBO’s comparisons, color coding has been used in Table 9 on page 16.

At one extreme—for communications from the brigade

ops net to operations desks at lower levels and for the

battalion ops net—red implies that demand exceeds

supply by a factor of 10 or more. A cautionary yellow

reflects a match between supply and demand to within

a factor of three. (Caution is warranted because although, on average, messages can be expected to get

through the network on time, some delays in transmission may be experienced.) Shades of orange indicate

gradually worsening imbalances between supply and

demand, lying between the cautionary yellow range and

the substantial mismatch indicated by red. (In the event

of results showing that supply exceeds demand by at

least a factor of three, green will be used.)

How does the Army’s experience compare with CBO’s

results? The Army has carried out relatively little testing

of large operations nets. However, when it has, participants have invariably cited shortfalls in bandwidth supply as a significant problem. The Army’s advanced warfighting experiments conducted at the National Training Center in 1997 and 1998 were, respectively,

battalion- and brigade-level experiments using state-ofthe-art communications equipment. The AWEs revealed bandwidth problems and network failures to the

point where soldiers switched back to analog voice

communications as the transmission of digital data

slowed. During the Division Capstone Exercise, which

was undertaken in April 2001 at the culmination of the

four-year effort to develop the digitized division, computer crashes occurred that were attributed to overloaded communications systems.
14 THE ARMY’S BANDWIDTH BOTTLENECK

Table 7.

Equivalent Peak Continuous-Flow Bandwidth for Episodic

Throughputs in 2003, by Throughput Type and Command Level

(In kilobits per second)

Command Levela

Fragmentary

Ordersb

Operational

Ordersc

Fused

Intelligence

Reports

Dynamic Unit

Task Orders Map Resyncsd

Corps 0.03 0 0.03 0 0

Division 0.03 0 0.003 to 0.03 0 0

Brigade 0.003 0 0.003 to 0.03 0 0

Battalion 0.017 0 0.17 to 1.7 0 0

Company 0.017 0 0.17 to 1.7 0 0

Platoon 0.017 0 0.17 to 1.7 0 0

Squad/Vehicle 0.017 0 0.17 to 1.7 0 0

Source: Congressional Budget Office based on data from Army subject matter experts and from the advanced warfighting experiments held between 1998 and 2001

at the brigade and division levels.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks

(for example, operations, intelligence, and fire-support) become less clear.

b. Usually short amendments to operational orders, which are transmitted as character data.

c. Issued once or twice daily, operational orders comprise character-based information including force subordination, disposition of the enemy, the commander’s

intent, operational goals for the commander’s force elements, and decision branch points.

d. Map resynchronizations, or “resyncs,” occur because information associated with digital maps must be updated when a unit moves from one map sector to

another.

Some insight is also available from more limited tests of

networks in the development stage. For instance, at Ft.

Hauchuca in 1999, a company-level test evaluated a

limited communications network equipped with the

Army’s most advanced communications gear. Severe

degradation occurred in the rate of message completion—it dropped to less than 60 percent—as the network’s message load was increased to peak operational

levels. In particular, for Blue situation assessments that

were successfully transmitted, the latency, or delay, averaged four minutes—a rate that may compromise certain missions.

Long latencies—delays in message transmission or

receipt—are often observed in the context of exercises.

However, shortages of bandwidth may not only produce latencies in communications networks but in

some cases also exacerbate other causes of delays. Operations officers remark that although long latencies are

not a handicap for deliberate planning or low-intensity

operations, they preclude reliance on the network

“when the shooting starts.”

Army studies have attempted to estimate the performance of operations networks for large units in the

field. One of the studies hints at the existence of the

bandwidth bottleneck that CBO’s analysis projects for

communications from the brigade to the battalion:

“Our analysis revealed that when large secondary

imagery dissemination products are provided

down to battalion level, the maximum data rate

capability of the radio [NTDR] is utilized. This

leaves no reserve capacity to the battalion and

confirms the need for more data bandwidth between the brigades and battalions.”10

Operation Iraqi Freedom

The Army’s plans for the recent conflict in Iraq included the use of at least one digitized unit in the early

10. Army Signal Center and Fort Gordon, Directorate of Combat

Developments, First Digitized Forces System Architecture, p. 1.
CHAPTER ONE BANDWIDTH SUPPLY AND DEMAND IN TODAY’S ARMY 15

Table 8.

Total Peak Demand for Effective

Bandwidth in 2003, by Command

Level

(In kilobits per second)

Command

Levela

Peak Bandwidth

Demand

Corps 3,000 to 10,000

Division 2,500 to 4,000

Brigade 800 to 1,300

Battalion 500 to 750

Company 30 to 100

Platoon 10 to 30

Squad/Vehicle 3 to 10

Source: Congressional Budget Office.

Note: Demand is extrapolated from the division level.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and firesupport) become less clear.

phase. The 4th Infantry Division, a unit of the 5th

Corps, employs the communications architecture described in this study. The division was originally slated

to deploy through Turkey and then be involved in the

early portions of the conflict. Instead, when it finally

disembarked in Kuwait, the conflict was deemed to

have largely ended. Therefore, even a qualitative comparison of the results of CBO’s analysis and the division’s experience with bandwidth supply and demand

in combat is impossible. 

Yet reports indicate that bandwidth was an issue for

those units that were engaged in the conflict. In the

months prior to the war and in anticipation of operating in combat with the 4th Infantry Division, other

units in the 5th Corps, selected units in the Marine

Corps’s 1st Marine Expeditionary Force, and the British armored division were outfitted with 1,000 equipment sets for interfacing with the 4th Infantry Division. Contractor support was also provided to enable

and sustain communications. The resulting system is

now called Blue Force Tracker.

The new system did not fully “digitize” any of those

other units, however. Instead, their degree of digitization was termed “digitization lite” by Army officers assigned to quickly provide the interfacing equipment.

Typical sets, some of which went to forces at the company level, comprised one terminal from the Force XXI

Battle Command, Brigade and Below (FBCB2) program, a Global Command and Control System

(GCCS) terminal at the higher command levels, an

ABCS terminal, and a commercial L-band satellite

transceiver (now increasingly common among U.S.

trucking firms), together with interfacing gear.11 By

using commercial L-band satellites (the military has not

invested heavily in the L-band), widely dispersed commands could keep track of forces that had the GCCS

and FBCB2 displays; at the higher command levels,

portions of the GCCS supported planning and

decisionmaking. (However, the Army could not fully

utilize the ABCS because of unmet National Security

Agency certification requirements and other inadequacies.)

When not challenged by line-of-sight constraints, soldiers used their SINCGARS and EPLRS equipment for

voice communications. When the widely dispersed and

rapidly moving forces faced LOS problems, soldiers

substituted commercial e-mail and “chat room” messages for point-to-point and collective voice communications. The mobile subscriber exchange proved useful

between fixed communications sites but much of the

time was not mobile enough for troops on the move. 

At the tactical operations centers at the higher command levels, the minimal equipment configuration described above supplied digital bandwidth that was

about one-quarter to one-third of that available in fully

digitized units. On the demand side, there was no basis

for comparison, for several reasons: during the conflict,

trunk lines were often “saturated”—all available digital

bandwidth was used up; demand was not subject to the

monitoring afforded in tests; lower command levels

were not equipped with the FBCB2; and the full capabilities of the ATCCS could not be exploited.

11. The GCCS comprises both hardware and applications-level software on the network.
16 THE ARMY’S BANDWIDTH BOTTLENECK

Table 9.

Effective Bandwidth Supply Versus Peak Demand in 2003, by Command Level

(In kilobits per second)

Command

Levela Bandwidth Supply

Peak Bandwidth

Demand

Relative Supply

Versus Peak Demand 

(S : D)b

Corps 2,550 3,000 to 10,000 1 : 1 to 4

Division 533 2,500 to 4,000 1 : 5 to 8

Brigadec 5338 800 to 1,300 1 : 1.5 to 38

379 1 : 20 to 309

Battalion 37 500 to 750 1 : 10 to 20

Company 15 30 to 100 1 : 2 to 6

Platoon 15 10 to 30 1 : 0.5 to 2

Squad/Vehicle 1.7 3 to 10 1 : 2 to 6

Source: Congressional Budget Office.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks

(for example, operations, intelligence, and fire-support) become less clear.

b. Based on an approximate logarithmic scale, the color coding is as follows: yellow indicates that supply is between about one-third and three times demand (a

marginal supply/demand match); light orange signifies that demand is approximately three times supply and orange, that demand is approximately three to 10

times supply. Red (used here for the lower brigade-level relationship and at the battalion level) means that demand exceeds supply by a factor of 10 or more.

c. The up-arrow (8) indicates the throughput rate for communications to equivalent or higher command levels. The down-arrow (9) indicates the throughput rate

to lower command levels.

Despite those drawbacks, some insights might be

gained. Fully coordinated Department of Defense “official lessons” from Operation Iraqi Freedom are not

yet available, and quantitative data may never be. But

qualitative statements from some authoritative sources

have been issued.12 Limited bandwidth was a constant

problem in spite of the large increase relative to that

available during Desert Storm; bandwidth from commercial satellites in particular was much more heavily

used.13 Although the Army has made a substantial investment in military-only decision-support systems,

much of the planning and collective decisionmaking

that occurred during the Iraq war was handled through

commercial e-mail and chat-room applications that soldiers were familiar with, that were “user friendly” and

reliable over long distances, and that required little or

no training. Another factor driving forces to use chatrooms and e-mail was that the distances over which

messages had to be transmitted precluded the use of

LOS radios and rather than wait or hope for reception

to improve (as a result of more relays being deployed),

they turned to satellite communications to speed their

operations.

Blue Force Tracker was praised by most users in both

the Army and the Marine Corps.14 However, the rapid

12. The following discussion draws heavily on the after-action reports

(AARs) issued by major units engaged in the conflict: those of the

5th Corps (entitled “V Corps: C4ISR Integration AAR”), the

3rd Infantry Division (see Chapters 17 and 26), and the 2nd

Brigade, 101st Airborne Division. 

13. At the peak of the conflict, the Defense Information Systems

Agency claimed that 3 Gbps of satellite bandwidth was being

provided to the theater, 84 percent of which was commercial. That

amount is 30 times the satellite bandwidth made available during

Desert Storm. See “DISA Chief Outlines Wartime Successes,”

Federal Computer Week, June 6, 2003.

14. One senior Marine Corps officer told CBO that while arguments

might continue over the lessons learned from Operation Iraqi

Freedom, there seemed to be community-wide agreement on Blue

Force Tracker. To paraphrase, “We used to lose units all the time.

Subject to bandwidth constraints, with Blue Force Tracker we

could find them almost immediately. . . . We’re going to buy

more.”
CHAPTER ONE BANDWIDTH SUPPLY AND DEMAND IN TODAY’S ARMY 17

pace of much of the operation and the wide dispersal of

U.S. forces made LOS communications challenging,

which, as noted earlier, rely on equally rapid and widely

dispersed relays to remain interconnected. (As one example, shortfalls of bandwidth for such communications were nevertheless noted as “information overload,” despite the limited information flow those applications—mainly e-mail and chat rooms—generated

and the relatively small number of network users.)15

The formats provided by Blue Force Tracker ranged

from bandwidth-intensive imagery to low-bandwidth

e-mail text messages. But because bandwidth saturation

affected communications for both the Army and Marine Corps, users were often forced to employ message

formats that used the least possible bandwidth (in other

words, text messages).

Other observations during the operation were related to

the availability and survivability of the bandwidth supply. Battery deficiencies (electrical generators are too

slow to deploy with rapidly moving forces) were noted,

particularly at executive command levels, and concerns

were raised about the communications systems’ electronic “footprint.”16

15. J. Davis, a reporter embedded with the Army’s 11th Signal Brigade

in southern Iraq, reported in the June 2003 issue of Wired Magazine that “[b]ecause anyone on Siprnet [a DoD classified network]

who wanted to could set up a chat, 50 [chat] rooms sprang up.

. . . The result: information overload.” In the same article, Lt. Col.

N. Mims of the 11th Brigade is quoted as saying, “We’ve started

throwing people out of the rooms who don’t belong there.”

16. An electronic footprint is the size, or power, of electromagnetic

emissions at various distances. J. Burias, in “G-6 Says OIF [Operation Iraqi Freedom] Validates IT Transformation Path,” Army

Link News, May 30, 2003, quoted Lt. Gen. P. Cuviello: “Antenna

farms sprang up around major Army units in both Afghanistan

and Iraq as different antennas were needed for each of six different

satellite bands and four different types of radios. . . . All those

antennas sometimes caused co-site interference with each other.”

Mobility requirements in Iraq and Afghanistan forced troops to

rely heavily on batteries rather than the generators normally used

at fixed locations. In the same article, Cuviello is also quoted as

saying, “Batteries are heavy items to carry around the

battlefield—not only to keep them stocked and transported, but

also the transportation requirements to dispose of them.”

2

Bandwidth Supply and Demand in 2010

The first units of the Army’s future Objective Force

are expected to be operational in 2010. Those units will

employ new, high-bandwidth communications systems

that provide about an order of magnitude more bandwidth

than that available today. However, at certain levels of

command, the Congressional Budget Office projects, the

growth of bandwidth demand will outstrip the growth

of supply. Changes in demand are expected from three

sources: incremental growth associated with upgrades to

currently deployed systems; more-substantial growth from

the introduction of new systems that have much greater

capacity to process and generate information; and changes

in the ways that information is processed and exchanged.

Bandwidth Supply at Army 

Commands in 2010

Three major programs are expected to increase the Army’s

supply of bandwidth by 2010. The Joint Tactical Radio

System (JTRS) is being designed to boost the supply of

bandwidth for the lower tactical Internet. The Warfighters

Information Network-Tactical (WIN-T) and a new satellite terminal program, which is expected to provide the

capabilities of the canceled STAR-T program, are planned

to increase bandwidth supply for the upper tactical Internet.1

The Joint Tactical Radio System

The JTRS program is a complicated joint effort involving

the four military services and the Special Operations

Command. By 2010, the Army-led portion of it will be

fielding its enhanced radios across the command chain.

The JTRS will replace the Army’s current SINCGARS,

EPLRS, and NTDR equipment with higher-capacity,

multichannel software-defined radios (SDRs). Most digital

radios in the field today are not SDRs; instead, they

produce their signals through their hardware alone and

consequently lack much of the flexibility of SDRs.2

The JTRS will be capable of communicating with the

Army’s “legacy” radios (the current generation of equipment) and will use a wide-band network waveform

(WNW) to provide high-capacity bandwidth.3

 The Army’s

1. The ongoing STAR-T (SHF [Super High Frequency] Triband

Advanced Range Extension Terminal) contract was terminated

in 2001 for default, as a result of delays and cost overruns.

2. Appendix A provides more detail about the differences between

SDRs and traditional digital radios. “Flexibility” pertains to the

relative cost, in time and money, of modifying the radio frequency

waveform (see the footnote below) in the entire “fleet” of fielded

radios. In principle, SDRs should be cheaper to modify because

the modifications involve changing only their software, which can

be done in the field, rather than pulling and replacing circuit boards

in depots.

3. Every radio has at least one waveform. Waveforms are distinguished

by the set of engineering choices made about such aspects as

frequency; amplitude modulations (as in an AM radio) or phase

modulations (FM); framing (breaking the data-carrying sections

into blocks); frequency hopping; time hopping; and a number of

other elements. Many of those other elements are designed to

improve the reliability of transmissions to intended recipients, yet

decrease the probability of detection and interception by others.

CHAPTER
20 THE ARMY’S BANDWIDTH BOTTLENECK

Table 10.

Effective Bandwidth Available to

Army Operations Networks in 2010,

by Command Level

(In kilobits per second)

Command

Levela

Total Effective

Throughputb

Corps 3,100

Division 1,100

Brigadec 1,1008

Battalion 6009

600

Company 400

Platoon 400

Squad/Vehicle 200

Source: Congressional Budget Office.

Note: In developing its estimates, CBO assumed that no change would be

made in information management or network architecture.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and firesupport) become less clear.

b. Point to point, under an assumption of perfect load balancing. In practice, throughput rates can be expected to be lower.

c. The up-arrow (8) indicates the throughput rate for communications to

equivalent or higher command levels. The down-arrow (9) indicates the

throughput rate to lower command levels.

goal for the WNW is an engineering bandwidth of

about 2 megabits per second, which would give an operational point-to-point throughput of about 200 kilobits per second. That amount is generally about an order of magnitude more bandwidth than is now provided by any of the radios in use in the lower tactical

Internet.

The WIN-T Program and Satellite Upgrades

According to the Army’s current plans, the WIN-T

program will not only purchase radios but also supply

computer terminals and servers, local area networks and

the associated networking gear, cryptological devices,

other interfacing equipment, and the software to run all

of those items. The WIN-T will be fielded at the brigade, division, and corps command levels, interfacing

with the satellite terminals that are used by those commands.

To take advantage of the bandwidth provided by the

WIN-T’s high-capacity radios, the Army plans to upgrade the associated satellite terminals as well. The

Multiband Integrated Satellite Terminal, or MIST,

program will provide those improved satellite communications. Coupling the WIN-T equipment and software to the new satellite terminal will deliver a maximum engineering throughput of about 24 Mbps and

effective bandwidth of about 2.5 Mbps.

Total Bandwidth Supply in 2010

Using assumptions analogous to those it adopted to

derive the maximum operational bandwidth of the

Army’s current networks (see Table 3 on page 11), CBO

has estimated the bandwidth that the JTRS, WIN-T,

and MIST programs will provide at all levels of command (see Table 10).

Bandwidth Demand at Army 

Commands in 2010

Several organizations have recently published projections of expected incremental growth in the demand

for communications capability on the battlefield.4

Those projections, which are based on experience over

the past several years, indicate annual growth rates that

vary from 10 percent to 46 percent, depending on the

level of command and other factors. Absent major new

program initiatives, the projections imply that the demand for bandwidth can be expected to double, on average, every two to five years across all levels of command. Therefore, to estimate the demand for bandwidth in 2010, CBO adopted the more conservative

end of that projection—in other words, that demand

4. See Office of the Undersecretary of Defense for Acquisition,

Technology, and Logistics, Report of the Defense Science Board Task

Force on Tactical Battlefield Communications (February 2000), p. 49;

Army Signal Center and Fort Gordon, Directorate of Combat

Developments, Modeling and Simulation Branch, Architecture

Division, First Digitized Forces System Architecture (1DFSA):

Version 2.02, Simulation Analysis/Study, White Paper (main text

and attachment entitled “Satellite Communications Capacity

Study,” June 30, 1999), p. 3 of the attachment; and RAND Arroyo

Center, “Future Army Bandwidth Needs—Interim Assessment”

(briefing prepared for the G6/Army Chief Information Officer,

July 10, 2002). The RAND interim assessment cites projections

of bandwidth demand growth by the Defense Advanced Research

Program Agency.
CHAPTER TWO BANDWIDTH SUPPLY AND DEMAND IN 2010 21

Table 11.

Number of Operating UAV Systems, by Command Level

Unit Size Digitized Units, 2003 Interim Force Objective Force, 2010

Tactical UAVs

Corps 0 0 1

Division 0 0 1 to 2a

Brigade 1 1

b

1 to 2c

Small UAVs

Battalion 0 0 1

Company 0 0 1

Platoon/Squad 0 0 1

Source: Congressional Budget Office.

Notes: Unmanned aerial vehicles are managed in systems of two or four. Typically, at the brigade level and above, a system will be organized in a UAV platoon with

four UAVs. Systems of small UAVs (a kind of tactical UAV) comprise two vehicles each. The Army’s current plans assume that a small-UAV downlink will not

be networked beyond the controlling unit.

During military actions, only one UAV per system will typically be flying; however, additional UAVs may serve as data relays, and other, nonflying UAVs may

be used as spares. The numbers in the table represent the number of UAVs that are under the direct control of the command and that are simultaneously

initiating transmissions.

a. CBO assumes that the Shadow or another extended-range system will probably be used.

b. ACRs (armored cavalry regiments), which are approximately the size of a brigade, would each have two UAVs.

c. Under current plans, the Army expects to use the Shadow system at this level.

for bandwidth would grow by about 15 percent a year

and would double every five years.

That estimate of 15 percent annual growth excludes the

effects that major new program initiatives might have

on demand. However, at least one recent initiative associated with the Army’s transformation—the service’s

intended widespread use of unmanned aerial vehicles—

will significantly increase the demand for bandwidth

over and above the service’s historical annual growth

rates.5

 Recently, the Army has been experimenting with

UAVs in the digitized forces and Stryker brigades, and

they have been used in operations in Iraq, Macedonia,

Bosnia, and Kosovo. Over the longer term, the Army

envisions a family of UAVs, which will be employed by

its Objective Force of the future.

The Army calls most of its UAVs tactical UAVs, or

TUAVs, because they are controlled by tactical commanders on the battlefield. (A subset of the TUAVs,

those with the shortest ranges, are called small UAVs,

or SUAVs.) The Army intends to field some type of

TUAV in the three higher command levels (see

Table 11).6

 Currently, both the digitized forces and the

Stryker brigades are equipped with Hunter TUAVs,

but the Army intends to replace them soon, substituting the more advanced Shadow system.7

5. Office of the Secretary of Defense, Unmanned Aerial Vehicles

Roadmap 2000-2025 (April 2001); and Congressional Budget

Office, Options for Enhancing the Department of Defense’s Unmanned Aerial Vehicle Programs (September 1998).

6. UAVs such as the Global Hawk and the Predator, which are

operated by the Air Force at the direction of a theater commander,

are examples of strategic UAVs. Although the Army is pursuing

some limited funding for research and development of strategic

UAVs, it has not made a commitment to field them.

7. A report from the Department of Defense’s Director of Operational

Test and Evaluation recently characterized the Shadow as neither

operationally suitable nor operationally effective, on the basis of

an initial operational test and evaluation completed in 2002.

However, the Shadow was deployed in Iraq during the recent

conflict, and as a result, CBO assumes that the problems noted

earlier will be resolved and the system will be fielded by 2010.
22 THE ARMY’S BANDWIDTH BOTTLENECK

Operating the Shadow system at the brigade and higher

command levels would generate a sizable demand for

bandwidth, depending on the degree to which the information those TUAVs collected was shared throughout the battlefield communications network. The Shadow will have three communications channels. One is a

large data channel with an engineering throughput of

16 Mbps that, operationally, should deliver from about

1.5 Mbps to 2 Mbps of useful video bandwidth. The

other two are redundant command-and-control channels providing 19.6 Kbps of operational throughput. A

division will control between four and eight of these

TUAV systems (although division commanders will

almost certainly make three to six of them subordinate

to brigade commanders). 

The doctrine underlying use of the Shadows is still

evolving, but at this point, the Army wants to share

among brigade and higher command levels the information collected from at least four—and possibly as

many as eight—of the TUAVs. Currently, data from

TUAV downlinks are shared between the operations

and intelligence nets of a command.8

 Under the assumptions that there are three brigades per division and

that they will be sharing (that is, networking) the information among themselves and also with their division,

then information from four to eight TUAVs will be

transmitted on each brigade’s operations trunk line. If

each TUAV requires 1.5 Mbps of bandwidth, each brigade will need from 6 Mbps to 12 Mbps. Divisions

typically command those brigades, and a corps commands the divisions. Hence, the demand for TUAV

bandwidth for the sharing of such information at those

levels will be from three to nine times larger than at the

brigade level.

Table 12.

Peak Effective Bandwidth Demand

in 2010 Under Two Assumptions

About TUAVs, by Command Level

(In kilobits per second)

Peak Bandwidth Demand

Command

Levela

TUAVs Are

Autonomous

TUAVs Are

Networked

Corpsb 10,000 to 30,000 30,000 to 100,000

Divisionb 3,000 to 10,000 10,000 to 30,000

Brigadeb 1,000 to 3,000 3,000 to 10,000

Battalion 1,000 to 2,000 1,000 to 2,000

Company 100 to 300 100 to 300

Platoon 30 to 100 30 to 100

Squad/Vehicle 10 to 30 10 to 30

Source: Congressional Budget Office.

Note: TUAV = tactical unmanned aerial vehicle.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and firesupport) become less clear.

b. If the architecture for information distribution located in the tactical

operations centers at these command levels is altered, as the Army is

considering doing, then operations officers will share information in a

new "backbone net." In that case, the ranges of numbers in the righthand column (TUAVs are networked) would apply.

The Army’s plans for the sharing of TUAV data—with

its heightened bandwidth demand—led CBO to develop two different scenarios for total demand in 2010

under the assumption in which the Army’s network

architecture (broadly speaking, its information management approach, including hardware and software) does

not change from its current structure in digitized units.

As noted earlier, that structure is one of multiple networks—for example, those for operations, intelligence,

and fire support. The information carried in each net

can be differentiated by whether or not it was generated

by TUAVs.

In the first scenario, existing demand is assumed to

grow by 15 percent a year, as discussed previously. The

second scenario adds a further assumption: that information collected by the Army’s future TUAVs will be

shared among the operations networks of the upper

8. Currently, all Army UAVs are considered intelligence assets,

although their communications downlinks are shared with the

operations channels, which can use them for situation assessments.

In the future, the traditionally separate operations and intelligence

nets could be consolidated, in which case the demand for

bandwidth in the operations net would simply be the sum of the

two currently independent demands.
CHAPTER TWO BANDWIDTH SUPPLY AND DEMAND IN 2010 23

command levels. In other words, the first scenario incorporates the assumption that TUAV operations are

autonomous (their information is not shared); the second, that their operations are networked (see Table 12).

But the Army is considering altering the network architecture in the future. One such change it is discussing

would load the non-TUAV information from all three

networks onto a single backbone net and divert the burgeoning TUAV information to a new, distinct highcapacity network. In that new architecture, the demand

for bandwidth on the backbone net would be approximately three times the demand on the ops net under

the old architecture and without networked TUAVs.

But the backbone net demand would also be the same

as in the case in which TUAVs were networked in the

ops net but no architectural change had occurred.

Thus, the most likely estimates of demand for operations bandwidth in 2010 correspond to those that incorporate the assumption that TUAVs are networked,

regardless of whether or not the Army changes the architecture of its battlefield information management

system.

Comparing Bandwidth Supply 

and Demand in 2010

As it did for 2003, CBO compared estimates of bandwidth supply and demand at the operations desks of

various tactical command levels in 2010. For its demand estimates, CBO assumed that TUAVs would be

networked and accommodated in either of the two information management architectures that the Army is

considering for 2010 (either the architecture characterized by separate networks to support the ops, intelligence, fire-support, and other missions or the structure

featuring a single backbone net for all non-UAV data

and a separate, high-capacity network dedicated to

transmission of UAV information). The use of those

two assumptions regarding architecture is advantageous

for two reasons: both assume that TUAVs will be networked (the current strategy), and both impose approximately the same bandwidth demand on the operations

network. Under the assumptions that demand grows in

accordance with the requirement to accommodate netTable 13.

Effective Bandwidth Supply

Versus Peak Demand in 2010,

by Command Level

Command

Levela

Relative Supply

Versus Peak Demand

(S : D)b

Corpsc 1 : 10 to 30

Divisionc 1 : 10 to 30

Brigadec,d 1 : 3 to 108

1 : 5 to 159

Battalion 1 : 1.5 to 3

Company 1 to 4 : 1

Platoon 4 to 10 : 1

Squad/Vehicle 7 to 20 : 1

Source: Congressional Budget Office.

Note: The range in relative demand at the brigade and higher levels of command is associated with either the proposed “backbone” architecture

or the case in which the current architecture is maintained and

downlinks from unmanned aerial vehicles are heavily networked. 

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and firesupport) become less clear.

b. Based on an approximate logarithmic scale, the color coding is as follows: green (used here at the platoon and squad/vehicle command levels) means that supply exceeds demand by approximately a factor of

three of more. Yellow indicates that supply is between about one-third

and three times demand (a marginal supply/demand match), and orange signifies that demand is approximately three to 10 times supply.

Red (used here for the corps and division levels) means that demand

exceeds supply by a factor of 10 or more.

c. If the architecture for information distribution located in the tactical

operations centers at these command levels is altered, as the Army is

considering doing, then operations officers will share information in a

new "backbone net." In that case, the upper end of the projected range

of bandwidth demand would apply.

d. The up-arrow (8) indicates the throughput rate for communications to

equivalent or higher command levels. The down-arrow (9) indicates

the throughput rate to lower command levels.

worked TUAVs and that all of the hardware improvements that are now anticipated are fielded, the bandwidth bottleneck will change its location in 2010 from

the brigade to the corps level but will be as severe then

as it is at the battalion level today (see Table 13).
24 THE ARMY’S BANDWIDTH BOTTLENECK

The degree of mismatch between CBO’s supply and

demand projections for 2010 varies considerably by

command level, as is the case currently. If the JTRS

performs as the Army projects it will, the new radio will

generally provide more than enough bandwidth for the

lower tactical levels of command, including a margin

for the potential growth of demand beyond 2010. At

the division and corps levels, however, the projected

demand swamps the likely supply.

How well do the Army’s most recent analyses of future

bandwidth supply and demand compare with CBO’s

estimates? Only partial comparisons are possible, given

the limited data. For a brigade-level unit in the future

Objective Force under surge conditions (in combat and

on the move), Army analysts project a demand for engineering bandwidth of 35 Mbps, which corresponds to

an effective demand of about 4 Mbps. The 4 Mbps figure is consistent with the demand that CBO projects at

the brigade level of between 3 Mbps and 10 Mbps (see

Table 12). Another Army source has indicated that the

effective demand could be as high as 12 Mbps—in

which case CBO’s projection would underestimate the

degree of mismatch.9

 The Army concludes that for

2010, the service, “will NEVER have enough BW

[bandwidth]” and urges that it be treated as “an operational (limited) resource.”10

9. Personal communication to the Congressional Budget Office by

Robert M. Saunders Jr., Deputy Director for Technology (Communications), Office of the Assistant Secretary of the Army for

Acquisition, Logistics, and Technology, November 17, 2002.

10. Lt. Gen. P. Cuviello, “Projected Bandwidth Usage and Capacity”

(briefing prepared by the G6/Army Chief Information Officer for

the Army Chief of Staff, August 2002), p. 4.
3

Mitigating Mismatches Between

Bandwidth Supply and Demand

The Congressional Budget Office has examined

several ways to treat the projected mismatches between

the Army’s demand for and supply of communications

bandwidth on the battlefield. Those approaches include

increasing supply, decreasing demand, reallocating currently planned spending to focus more resources on command levels with the most severe bandwidth problems,

and developing tools to better manage whatever mismatches persist. Increasing the supply of bandwidth by

buying more or better radios would probably be the least

effective way to mitigate the supply/demand imbalance.

Indicators of the efficacy of reallocating resources are

ambiguous, and their results depend on the metric being

used. CBO is thus unable to provide any unequivocal

findings on that option. Decreasing demand would help

lessen the mismatch, and some potential options are

discussed, although they would not eliminate the imbalance. Better management of supply and demand would

also help shrink the supply/demand gap, and several

aspects of that approach are noted.

Buy Better Radios in Greater Quantities

The Army might increase its supply of bandwidth in 2010

by buying radios that are more technologically advanced

than those it is currently expecting to have. Yet the service’s planned programs appear to already be incorporating

all of the most likely advances in communications technology. To develop new radios such as the Joint Tactical

Radio System, the Army has contracted with large corporate teams that include many of the world’s premier

radio makers and computer network experts, and program

managers report that those development efforts are fully

funded.1

 Because of the ambitiousness of some of the

technological advances being pursued, there is a risk that

not all of them will be realized (see Appendix A). Thus,

it seems unlikely that advances in technology over and

above those that the Army is already pursuing could

reduce the bandwidth supply/demand mismatches that

CBO projects.

Also questionable is whether the projected shortfalls in

the supply of Army bandwidth could be eliminated by

purchasing more of the communications equipment that

is now being developed. At the division and corps levels,

CBO estimates, demand in 2010 will outstrip supply by

a factor ranging between 10 and 30. At those levels of

command, the Warfighter Information Network-Tactical

program will supply the majority of bandwidth, and the

Army has considered increasing its purchases of WIN-T

equipment 20-fold to better match the expected demand.

But implementing such an option would present a number

1. CBO analysts questioned program managers about the adequacy

of funding levels as one way to gauge the severity of the risk that

products scheduled for fielding by 2010 might not actually be available. Managers reported full funding, which signifies the Army’s

commitment throughout the Department of Defense’s Future Years

Defense Program to provide funds that the service and the Defense

Department agree will meet the programs’ formal requirements.

For products scheduled for fielding after 2010 (for example, JTRS

Cluster 2 cellular phones), program managers identified unfunded

requirements that if fully funded might accelerate fielding dates.

However, bringing those capabilities to the field faster would not

mitigate the shortfalls that CBO’s analysis revealed.

CHAPTER
26 THE ARMY’S BANDWIDTH BOTTLENECK

288

 28

2 More than 10

 Number of Nodes

Figure 1.

Notional Throughput Capacity

per Node

(In kilobits per second)

Source: Congressional Budget Office based on a briefing on the upper and

lower tactical Internets provided by the Army Chief of Staff, Staff

Group.

Note: The rate of throughput is highly dependent on the number of nodes in

the network.

of challenges, including management of the increased

complexity and inefficiency of the communications

network that would result; the physical space, or “footprint,” required to accommodate the additional equipment

on the battlefield; and the additional cost. 

Increased Network Complexity and Costs

As the number of nodes in a communications network

increases, the network’s efficiency—measured as the

throughput capacity available at each node—decreases (see

Figure 1). As the figure shows, an order-of-magnitude

increase in the number of nodes contained in the network

can produce nearly an order-of-magnitude decrease in

bandwidth at a given node. The results in the figure are

consistent with theoretical estimates of how a network’s

efficiency (measured in kilobits per second) varies with

the number of nodes when current methods (specifically,

Internet processing protocols) for transmitting information around a network are used.

Theory indicates that network throughput can be expected

to decay as 1/Q, where Q is the square root of N ln(N),

N is the number of nodes in the network, and ln is the

natural logarithm.2

 Consequently, if the number of radios

increased by a factor of 20, the network’s throughput

would rise by only a factor of 20/7—or about 3—where

7 is the reduction in throughput caused by the increase

in the network’s complexity.3 In other words, the 20-fold

increase in purchases of WIN-T equipment that the Army

has considered would not be sufficient to overcome the

10- to 30-fold shortfall in available bandwidth that CBO

projects for 2010 at the corps and division levels of command. Theoretically, at least a 600-fold increase would

be required, which the Army is unlikely to pursue, given

that WIN-T procurement costs are currently estimated

to be about $5 billion.4

Expansion of the Footprint

The geographic footprint of a program is the physical

space that the program’s equipment occupies when it is

operated on the battlefield. The Army’s current plans for

the WIN-T and JTRS have raised concerns about the proliferation of equipment in vehicles and operations centers.

Part of the reason for that concern is a lack of physical

space, an element that has also surfaced in discussions

about changing the network architecture. Another issue

is that the associated increase in the equipment’s electronic

footprint (the size, or power, of its electromagnetic emissions at various distances), caused by the proliferation of

2. See P. Gupta and P.R. Kumar, “The Capacity of Wireless Networks,” IEEE Trans Information Theory, vol. 46, no. 2 (March

2000), pp. 388-404. 

3. The development and adoption of new methods—including socalled dynamic protocols—for transmitting information among

the nodes in a communications network might reduce the inefficiency penalty that accrues as the number of nodes increases.

However, the development and adoption of such protocols for use

in military communications networks are unlikely to occur prior

to 2010.

4. The Army’s estimates in 2002 of the total cost for the WIN-T

program ranged from $4 billion to $9 billion (in 2002 dollars),

with $2 billion in expenditures scheduled between 2004 and 2009.

More recent (2003) estimates by contractors put total program

costs at about $5 billion and $6.6 billion, respectively. The figures

that follow use $5 billion. (Unless otherwise indicated, all costs

are expressed as fiscal year 2003 dollars.)
CHAPTER THREE MITIGATING MISMATCHES BETWEEN BANDWIDTH SUPPLY AND DEMAND 27

Squad/Vehicle

Platoon

Company

Battalion

Brigade

Division

Corps

0123456789

Squad/Vehicle

Platoon

Company

Battalion

Brigade

Division

Corps

0 0.5 1 1.5 2 2.5

radiating antennas and electronic “noise,“ will facilitate

enemies’ detection and targeting of U.S. forces. In that

context, increasing the amount of communications equipment by a factor of 20—or more—could pose significant

problems.

Reallocate Currently Planned Spending

If additional spending is unlikely to close the gap between

bandwidth supply and demand, might currently planned

spending be reallocated to focus more on the command

levels that projections show will have the most severe

problems in 2010? Answering that question requires

constructing so-called figures of merit to relate projected

spending at each command level to communications

capacity—both the capacity that will be provided and the

capacity that will be demanded. Several such metrics can

be considered.

Spending data indicate that over the next several years,

the Army plans to spend more money at the lower levels

Figure 2.

Total Projected Investment in Ops Net

Equipment, by Command Level 

(In billions of fiscal year 2003 dollars)

Source: Congressional Budget Office.

Figure 3.

Cost of the Capacity Provided per 

Ops Net, by Command Level

(In fiscal year 2003 dollars/bit per second/net)

Source: Congressional Budget Office.

of command—that is, below the division and corps levels

and away from the bandwidth bottleneck projected for

2010 (see Figure 2). That distribution of expenditures

arises because radios are spread throughout the force and

most personnel with radios are located not at higher

command-level headquarters but in the decreasingly

smaller, more numerous units that compose the lower

levels of command.

Considering the cost of the total bandwidth capability that

the Army plans to provide yields a different picture. Lower

levels of command comprise many vehicles and soldiers,

which the Army envisions equipping with relatively simple

versions of the JTRS. At higher command levels, smaller

numbers of more complex and more expensive versions

of the JTRS will be fielded, as well as more sophisticated—and costly—line-of-sight and beyond-line-of-sight

satellite communications radios. That latter equipment

will supply much greater amounts of bandwidth per unit

and support more networks than the simpler but more

numerous radios planned for the lower levels of command.
28 THE ARMY’S BANDWIDTH BOTTLENECK

Squad/Vehicle

Platoon

Company

Battalion

Brigade

Division

Corps

012345

Figure 4.

Cost of the Capacity Utilized per 

Ops Net, by Command Level

(In fiscal year 2003 dollars/bit per second/net)

Source: Congressional Budget Office.

A metric can be constructed that accounts for the cost of

the capacity provided per ops net at each command level

(see Figure 3). As the figure shows, the cost is greatest for

the levels of command at which the bandwidth bottleneck

is projected to be most severe in 2010. 

Considering the cost of the capacity utilized (as opposed

to provided) yields yet another view of how the Army’s

projected investments are distributed by command level

(see Figure 4). As Chapter 2 discussed, the supply of bandwidth at the squad and platoon levels in 2010 will exceed

the projected demand by factors ranging from four to 20.

The reason is that the simpler version of the JTRS to be

fielded at lower command levels is equipped to communicate with higher levels; that is, it has the capability to

use the wide-band networking waveform (discussed in

Appendix A), which provides substantial bandwidth—

more than the demand now being projected. A radio

lacking that capability would be less expensive and could

allow resources to be channeled elsewhere. However, it

would also be incapable of communicating with all levels

of command or with the forces of the other military

services.

Would a reallocation of the Army’s projected resources

be a viable option for mitigating the mismatch between

bandwidth supply and demand projected in the future

Objective Force? The results presented in the figures above

do not offer clear guidance. Consequently, such a reallocation does not appear to be an obvious alternative for

addressing the Army’s future bandwidth bottleneck.

Reduce Demand and Better Manage

Persisting Mismatches

Because of the potential problems associated with buying

more bandwidth to eliminate the Army’s projected bottleneck, CBO considered options to reduce lower-priority

bandwidth needs and to better manage the remaining

demand. Three such alternatives are discussed below. The

first two would end the transmission of information that

might be of lesser priority yet would be expected to contribute significantly (either directly or indirectly) to the

future supply/demand mismatch at the higher command

levels. The third option focuses on adopting software tools

that are now entering the commercial market and that

could allow better management of the demand for bandwidth when it exceeds supply. In keeping with its mission

of providing impartial analysis, CBO makes no recommendations about adopting one or more of these options.

Rather, they are meant to illustrate some of the choices

that the Army might consider as it attempts to match its

expectations regarding digitization to the communications

capability it is buying.

Eliminate Video Teleconferencing on the Battlefield

As discussed earlier, video teleconferencing is a bandwidthintensive activity; the usual teleconferencing site requires

about 1,000 Kbps of bandwidth. Video teleconferencing

enables commanders at disparate locations to interact as

if they were personally present at one location. Participants

can hear vocal tones and observe facial expressions and

other aspects of behavior that commanders argue are

important elements in decisionmaking and planning. In

addition, they can observe and comment collectively on

complex visual objects—for example, maps depicting the

disposition of enemy and friendly forces.

In cases in which video teleconferencing capability does

not exist or is unavailable because of a lack of bandwidth,

an alternative is voice conferencing, which has been and
CHAPTER THREE MITIGATING MISMATCHES BETWEEN BANDWIDTH SUPPLY AND DEMAND 29

continues to be used routinely by commanders as a substitute. Although voice conferencing does not allow conferees

to collectively view objects or drawings, that capability

can be provided by adding a “smart” whiteboard visual

display; the digital whiteboard allows conferees to view

a rendition (in black and white, not color, which would

require more bandwidth) of the object under discussion—

typically a dynamically generated drawing, map, or operational plan. (The conclusion that such a capability could

be useful was reached by the 5th Corps just prior to the

recent Iraq war.)5

 Conferees can not only use the whiteboard as a blackboard but may also utilize electronic

features such as the ability to scan documents and communally view files.

Overall, voice conferencing coupled with whiteboard

capability generally requires less bandwidth (by about a

factor of 10) than video teleconferencing requires. The

Army’s test community has assessed the relative value, for

collaborative planning, of teleconferencing, a drawing or

black-and-white projection capability (available with the

whiteboard), and video. Its judgment: “The draw and

voice features deliver the highest value for collaboration.

The draw feature was particularly critical. Video is a good

feature but has the least relative value as compared to draw

and voice capabilities.”6

A second military use for video teleconferencing is telemedicine, in which medical personnel consult with doctors

at remote locations to bring to bear experience and expertise that may not be available on the battlefield. Telemedicine has been a feature of recent low-intensity operations

(such as the U.S. military’s peace enforcement mission

in Macedonia) during which only limited medical support

was available in the theater of operations. But telemedicine’s value in other military operations has been questioned. In-theater medical capability is extensive in highintensity battlefield situations such as Operation Iraqi

Freedom. Above the medical aid stations at the battalion

level of command, the medical evacuation system delivers

patients to combat-support hospitals and to field and

general hospitals. Those large facilities have scores of

physicians who are trained in battlefield and specialty

medicine and who may not have the time or the need to

consult extensively with off-site doctors. Hospital facilities

are reinforced by an Air Force-run medical evacuation

system that can move patients quickly to major medical

centers in Europe, Japan, or the United States. After considering all of those factors, the Army has chosen not to

provide telemedicine capability at the battalion level of

command.

Eliminating video teleconferencing would reduce the current demand for bandwidth by as much as 70 percent at

the brigade command level and 15 percent at the corps

level, CBO estimates. Less demand at the brigade level

would be helpful in reducing the bottleneck there, but the

15 percent drop in demand at the corps level would mitigate little of the bandwidth supply/demand mismatch

there, where it is projected to be more severe in 2010.

Those same reductions would apply to the demand for

bandwidth in 2010 under the scenario in which video data

collected by UAVs were not shared over the network. If

such data were shared, which is a more likely outcome,

then total bandwidth demand would be greater, and the

fractional savings associated with eliminating video

teleconferencing would be reduced to about 20 percent

at the brigade level and 5 percent at the corps level.

Eliminate the Requirement to Support

Networked UAVs

As discussed in Chapter 2, the demand for Army bandwidth in 2010 will exceed the projected supply by as much

as a factor of 30 at the division and corps levels of command and up to a factor of 10 at the brigade level. Those

estimates apply, regardless of the information management

scheme that the Army decides to use, if the video data

collected by UAVs are shared among operations networks

at the upper levels of command. Under this option, the

5. After several years of experience with video teleconferencing (VTC),

the 5th Corps’s commander, Lt. Gen. WilliamWallace, suggested

in 2002 that VTC “was wasteful,” and the corps went to war in

Iraq with voice conferencing and a rudimentary whiteboard

capability. A lack of training and established procedures prevented

those tools from being judged fully successful, but the bandwidth

advantage they offered (their bandwidth demand is much less than

that of video teleconferencing) continues to spur additional

experimentation. See Maj. M. Shaaber, Capt. S. Hedberg, and Troy

Wesson, V Corps: C4ISR Integration AAR (after-action report)

(May 2003), pp. 37-38.

6. Lee Offen and Mary E. Stafford, Assessment Report for the Division

XXI Advanced Warfighting Experiment (DAWE) (United States

Army Operational Test and Evaluation Command, January 22,

1998), p. ES-11.
30 THE ARMY’S BANDWIDTH BOTTLENECK

Army would forgo sharing those data beyond the initial

sensor-to-shooter downlink. Instead, UAV operators

would summarize collected intelligence in a lower-bandwidth message, which could then be more easily transmitted. Commanders would thus receive the results of

UAV missions but would not have direct access, in real

time, to the video images that the vehicles collected.

Eliminating the requirement to share video data would

reduce the future demand for bandwidth at the brigade

and higher levels of command by a factor of three.

Provide Bandwidth Management Tools 

at the Applications Layer

If the Army eliminated both video teleconferencing and

the requirement to share UAV data, CBO estimates that

the service could reduce total bandwidth demand by

roughly a factor of three. Nevertheless, such a reduction

would be insufficient to bring demand into line with

supply. Currently, when the supply of bandwidth is

inadequate, operations officers attempt to manage demand

manually as they transmit messages. They prioritize

transmissions, on the basis of their experience and professional judgment, assigning a sequence to the times at

which messages in a queue will be sent. Sometimes, to

decrease delays and increase message completion rates,

communications personnel in a tactical operations center

literally pull the plug temporarily on some equipment in

order to have enough bandwidth for the highest-priority

messages. As discussed in Chapter 1, however, those efforts

to reduce the demand for bandwidth have frequently failed

to prevent unacceptable degradation in the performance

of the Army’s battlefield communications networks during

experiments. During the recent war in Iraq as well, constraints on bandwidth forced soldiers to confront their

lack of techniques for managing bandwidth.7

Communications officers have automated network management tools available to help them monitor a variety

of measures of bandwidth demand and thus aid their

prioritizing of message traffic. Some of those tools can

automatically increase or decrease the bandwidth allocated

to given types of messages or other data transmitted over

the Army’s battlefield network. But there is little or no

feedback in such systems; consequently, the software applications that generate the messages and data transmitted

over the network cannot automatically detect that the

available bandwidth has been increased or decreased. As

a result, message queues tend to lengthen once a bandwidth allocation has been reduced because the rate at

which the messages are generated does not change. And

once messages become old and exceed thresholds for

latency (delay), they are eliminated from the network without being transmitted. In more extreme cases, the rates

at which information flows between hardware components

(which are usually set, by the flip of a physical switch,

when the hardware is linked to the network) are exceeded,

and messages are truncated or dropped. Neither condition

is satisfactory: lost messages may be important, and overflowing queues, a portion of which the network continually tries to retransmit, strain the network’s responsiveness

and reliability.

This option would expand the capabilities of today’s

network management tools so that message-producing

software applications could sense changes in the available

bandwidth and automatically increase or decrease the rate

at which messages were generated. That approach is beginning to be used by private-sector firms that develop software for use on the Internet.8

 The cost of developing and

testing the software required to implement this kind of

an option for the Army is currently unknown, and CBO

did not attempt to estimate it.

7. Shaaber, Hedberg, and Wesson noted in V Corps: C4ISR Integration

AAR (p. 5): “The ability to manage bandwidth usage dynamically

at the discretion of the commander would [be helpful].”

8. The Defense Information System Agency cites the reduction of

bandwidth demand as one of the goals of its Defense Information

Infrastructure Common Operating Environment (DII COE). The

DII COE is a set of standards pertinent to the Defense Department’s hardware, software, and networking capabilities. A number

of commercial companies are beginning to respond with morecapable software tools that control computer file server software

on the basis of the available network bandwidth.
A

The Army’s Current

Communications Initiatives

The Army is currently pursuing three major programs

that are expected to increase its communications

bandwidth: the Warfighter Information Network-Tactical

(WIN-T), the Joint Tactical Radio System (JTRS), and

a new satellite communications (SATCOM) terminal.

Those programs had formerly been considered part of the

Army’s digitization initiative, which—as discussed in

Chapter 1—has now been subsumed under the Army’s

transformation effort.1

 Although no longer separately identified in the Department of Defense’s annual reports to

the Congress, the digitization initiative still comprises

about 100 Army programs whose collective goal is to field

advanced information technologies throughout the service’s combat and support forces.

In the defense program covering fiscal years 2003 to 2007,

overall spending for the service’s digitization programs

was projected to average $4.1 billion dollars annually.2

Approximately 28 percent of that funding was allocated

to communications; 24 percent to command-and-control

software programs; 14 percent to digital processing capabilities in equipment such as the Abrams tank, Bradley

fighting vehicle, and Comanche helicopter; 27 percent

to data-link improvements in intelligence, reconnaissance,

surveillance, and targeting systems; and 7 percent to

training and development of doctrine for the new digital

equipment. The WIN-T, JTRS, and new SATCOM

terminal account for about one-third of the 28 percent

of total digitization funding allocated to communications

between 2003 and 2007. The remaining two-thirds of that

funding is designated for upgrades to the Army’s large

fixed-base satellite communications terminals; for

command-and-control programs associated with the firesupport and intelligence nets; and for other, less expensive,

less complex radio systems. 

Under the Army’s current plans, the likely total investment

in the WIN-T, JTRS, and new SATCOM terminal will

range from $19 billion to $24 billion through 2020. Procurement of the satellite terminals will be completed by

2007, and the first combat units will be equipped with

all three systems by 2010. From 2003 to 2009, the Army

plans to spend roughly $2.5 billion on the JTRS, $1.7

billion on the WIN-T, and $200 million on the new

SATCOM terminal.

The WIN-T Program 

The overall purpose of the WIN-T program is to develop

and purchase communications equipment for tactical

operations centers (TOCs) at the brigade and higher levels

of command. The program will provide equipment to

replace the current mobile subscriber equipment phone

system; it will also provide the radios (particularly such

equipment as the high-capacity line-of-sight, or HCLOS,

radio), the telephone switching networks and computers,

1. Some details related to the digitization initiative are reported in

annual defense reports. See, for instance, Secretary of Defense

William S. Cohen’s Annual Report to the President and Congress

in 1999, 2000, and 2001. Over that period, the Army’s annual

investment in digitization increased from $3 billion to $3.6 billion.

2. Congressional Budget Office, The Long-Term Implications of Current Defense Plans (January 2003).

APPENDIX
32 THE ARMY’S BANDWIDTH BOTTLENECK

the local area networks, and the control software that make

up the communications element of a TOC. 

WIN-T equipment will be capable of operating with the

JTRS to allow the higher command levels to communicate

with brigade and lower levels. Although the requirements

for the WIN-T are still being developed, the operational

data rate that its radios are expected to provide will be

about 833 kilobits per second (Kbps)—the effective

throughput at the applications layer for the HCLOS

radio.3

 Such a data rate will allow streaming video at a

speed of about 16 frames per second.

Because the requirements for the WIN-T are continuing

to evolve, its costs are uncertain. The Army’s current

estimates of the program’s total costs range from $4 billion

to $9 billion through 2020; estimates by contractors range

from $5 billion to $6.6 billion. Recent discussions within

the Army’s program office for the WIN-T have focused

on issues related to bandwidth supply, and program

officials have noted shortfalls that are consistent with the

results of this Congressional Budget Office (CBO) analysis. One solution that the Army is considering is redundancy—that is, increasing from five to 101 the number

of WIN-T sites (either on vehicles or in the TOCs) that

military units of the future will have.4

 Still to be settled,

however, are questions regarding the costs of that redundancy and the “footprint” (the amount of space devoted

to computer and communications equipment in the

TOCs) associated with such an expansion.

The Joint Tactical Radio System

The JTRS is a family of radios designed to provide interoperable tactical communications among the military

services. Communications among the services’ different

radios during the 1991 Gulf War, and the JTRS program

was initiated following that conflict. The military’s procurement of the JTRS is divided into “clusters,” which

are differentiated according to the lead agency responsible

for developing the radio hardware for various mission areas

or weapon platforms (for example, a tank or a ship).

(Table A-1 summarizes the services’ participation in the

JTRS program by cluster, lead agent, and funding.)

The Army is most heavily involved in the Cluster 1

portion of the JTRS program. The cluster’s goals are to

develop and acquire a family of new software-programmable radios that can be used to communicate with a number

of existing Army and Air Force radios operating in frequency bands of between 2 megahertz and 2 gigahertz.

The radios built under Cluster 1 must also be capable of

using a new wide-band networking waveform (WNW)

that will provide substantially increased bandwidth

compared with the amount provided today. The WNW

is a family of four waveforms at different frequencies that

offer different levels and types of capability.5

 The latest

description of the Army’s requirements for the WNW

states:

“[T]he WNW shall support greater than 2

Mbits per second of Network Throughput

as a threshold. The WNW shall have the

ability to make efficient use of extra frequency spectrum when available and shall

support Network Throughputs of greater

than 5 Mbits per second as an objective.

. . . The JTRS WNW operating in the

Point-to-Point mode shall support a user

throughput rate of greater than 2 Mbps in

each direction.”6

On the basis of that description, CBO used 2 Mbps as

the throughput rate for the JTRS Cluster 1 radio system

in its analysis of bandwidth supply in 2010.

3. The maximum engineering throughput is about 8 million bits per

second (Mbps), point to point.

4. Reported to the Congressional Budget Office in a briefing by the

WIN-T Program Office titled “Warfighter Information NetworkTactical,” February 20, 2003. 

5. The WNW is being developed in stages: stage 1, a wide-band

waveform available by 2004; stage 2, a midband waveform that

has a low-probability-of-intercept (LPI) and a low-probability-ofdetection (LPD) capability by 2005; stage 3, a midband waveform

with “anti-jam” capability by 2005; and stage 4, a narrow-band,

special-access waveform by 2006. The WNW’s interoperability

with the legacy waveforms is expected by 2006.

6. Department of the Army, JTRS Joint Program Office, JTRS WNW

Functional Description Document (August 23, 2001), pp. 12-13.
APPENDIX A THE ARMY’S CURRENT COMMUNICATIONS INITIATIVES 33

Table A-1.

Planned Investment in the Joint Tactical Radio System, 

by Organization and Cluster

Cluster and Investors

(Lead agency) Mission Area or Platform

Planned Spending,

2003 to 2007

(Millions of dollars)

Cluster 1 (Army) Vehicular/Rotary Wing

Army 516

Marine Corps 51

Air Force 22

Cluster 2 (SOCOM) Handheld Radios/Manpack

SOCOM 10

Air Force 35

Cluster 3 (Navy) Ships/Fixed Sites 517

Aviation Cluster (Air Force) Fixed-Wing Planes

Air Force 938

Navy 0

Subtotal 2,089

Joint Program Office Waveform Development 269

Total 2,358

Source: Congressional Budget Office based on the Department of Defense’s Future Years Defense Program for fiscal years 2003 through 2007.

Note: SOCOM = Special Operations Command.

The most recent estimates of costs for the JTRS are on

a par with an average production cost per radio of about

$127,000.7

 In comparison, the radios being replaced by

the JTRS range in cost from about $8,000 to $28,000.

However, per unit of bandwidth, systems like the

SINCGARS (Single-Channel Ground and Airborne Radio

System) and EPLRS (Enhanced Position Location

Reporting System) cost about 25 cents to 50 cents per bit

per second; the corresponding cost for the JTRS is

projected to be about 6 cents, which is only slightly higher

than that using fiber-optic cable.8

The Army plans to buy a total of 106,000 JTRS radios,

which would be sufficient to equip about one-half of its

forces. (Left unequipped would be most of the 15 enhanced separate brigades, their combat support and

combat service support units, and the National Guard

divisions.)9

 Under current plans, the JTRS program is projected to cost about $15 billion. Of that amount, procurement costs would account for $13.5 billion, and research

and development costs, $1.5 billion. The Army currently

plans to purchase about 10,000 JTRS radios per year, on

average, at an annual cost of about $1 billion over the

period from 2010 to 2020.

Those plans may be jeopardized, however, if perceptions

of the program as a high-risk effort prove to be correct.

(A recent analysis sponsored by the Army noted the high

level of risk associated with the JTRS program’s successful

7. Based on the December 2002 Selected Acquisition Report.

8. The Report of the Defense Science Board Task Force on Tactical

Battlefield Communications (February 2000, p. 102) states that the

cost of bandwidth using fiber-optic cable is 4 cents per bit per

second.

9. The SINCGARS SIP (special improvement program), which

procured the most recent and capable SINCGARS radio, purchased

108,000 of them. However, the number of fielded SINCGARS

is about 211,000, which includes all versions of the radios that have

been purchased.
34 THE ARMY’S BANDWIDTH BOTTLENECK

completion.)10 Elements that contribute to that assessment

include the complexity of the software development

required, the size and weight constraints imposed on the

radios, the amount of power that they will consume, the

heat that they dissipate, and interference problems that

are anticipated among the waveforms when the radios are

colocated. For example, each JTRS radio will have multiple central processing units and power amplifiers to cover

the broad range of frequencies (2 megahertz to 2 gigahertz)

over which each radio must operate.11 That equipment

will dissipate substantial heat into the confined spaces

(such as tanks) in which the radios will be installed,

making the reliability of their electronic components a

primary requirement. The Army has identified potential

solutions to such problems but has yet to demonstrate that

they will work collectively. 

Another risk factor associated with the JTRS program is

the challenge of ensuring that the radios will function

properly as part of a complex communications network.

The JTRS will provide the communications capability

to support a mobile battlefield version of what today is

largely an Internet based at fixed sites.12 The Defense

Science Board has stated that “the Internetworking aspects

of the program, a critical contribution of moving the DoD

[Department of Defense] point-to-point and broadcast

wireless infrastructure into an integrated Internetwork,

is [sic] not being adequately addressed.”13

Related cautions about the same set of issues were expressed as part of the supporting assessments generated

for the Defense Acquisition Board’s decisions in 2003

related to the Future Combat System (FCS).14 The assessments noted the following: “Bandwidth could be an

Achilles Heel. . . . Estimated requirements could reach

10’s of Mbps for UA [this CBO study conservatively

estimates 3 Mbps to 10 Mbps]. . . . [The] Army must have

a credible bandwidth requirement and planned solution

to pass Milestone B.”15 Those bandwidth-related concerns

were reiterated by the recent Institute for Defense Analyses

(IDA) assessment of the FCS.16 The report noted that what

it termed “critical enablers”—that is, complementary systems such as the JTRS and WIN-T—must be “managed

and fielded on the same time schedule as FCS.” While

in general, the IDA study panel took the Army’s technology assessments at face value, they did assign a yellow

advisory assessment (implying caution) to the JTRS’s

“wideband waveforms.”17

How would the results of CBO’s analysis be affected if

the JTRS program did not deliver its improved radios by

2010? The most likely substitutes for the JTRS would be

either the NTDR (Near-Term Data Radio); a digital,

improved EPLRS; or a new radio with a similar maximum

bandwidth. If a substitution was necessary, the operational

bandwidth provided by such a radio would be about

30 Kbps instead of the 200 Kbps provided by the JTRS.

As a consequence, the mismatch in 2010 between

bandwidth supply and demand in the Army’s future

10. Department of the Army, Army Materiel Systems Analysis Activity

[AMSAA], Army Future Combat Systems Unit of Action Systems Book,

Version 1.3(s) (September 18, 2002), pp. 2-2, 2-18, and 2-19.

11. In principle, one processor could be sufficient. But the constraints

of timely development plus the Army’s desire to incorporate existing, patented technologies and use existing control systems force

the choice of multiple processors.

12. In Operation Iraqi Freedom, for instance, the client/server Internet

could be characterized as movable or mobile clients networking

through static banks of fileservers located at fixed sites in locations

such as Kuwait, Qatar, and later Baghdad.

13. Office of the Under Secretary of Defense for Acquisition, Technology, and Logistics, Report of the Defense Science Board Task Force

on Tactical Battlefield Communications (February 2000), p. 93 and

Annex D.

14. These materials are the 31 technology assessments referred to by

E.C. Aldridge Jr. in his memorandum of May 17, 2003, to

Secretaries of the military departments regarding the Future

Combat Systems acquisition decision.

15. L. Delaney, “Independent Review of Technology Maturity

Assessment for Future Combat Systems Increment 1” (March 3,

2003). The study was commissioned by the Army prior to the May

17, 2003, Defense Acquisition Board Milestone 2 meeting on the

FCS.

16. L.D. Welsh, “Report of the Indendent Assessment Panel for the

Future Combat System” (draft, Institute for Defense Analyses,

April, 28, 2003).

17. Ibid., p. 60.
APPENDIX A THE ARMY’S CURRENT COMMUNICATIONS INITIATIVES 35

Table A-2.

Effective Bandwidth Supply

Versus Peak Demand in 2010,

with a JTRS Substitute 

Command

Levela

Relative Supply

Versus Peak

Demand (S : D)b

Corps 1 : 10 to 30

Division 1 : 10 to 30

Brigadec 1 : 3 to 108

1 : 50 to 1509

Battalion 1 : 15 to 30

Company 1 : 2 to 10

Platoon 1 : 0.5 to 1

Squad/Vehicle 1 to 2 : 1

Source: Congressional Budget Office.

Note: JTRS = Joint Tactical Radio System.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and firesupport) become less clear.

b. Based on an approximate logarithmic scale, the color coding is as follows: yellow indicates that supply is between about one-third and three

times demand (a marginal demand/supply match), and orange signifies

that demand is from three to 10 times supply. Red (here used for the

corps, division, lower brigade-level, and battalion level relationships)

means that demand exceeds supply by a factor of 10 or more.

c. The up-arrow (8) indicates the throughput rate for communications to

equivalent or higher command levels. The down-arrow (9) indicates the

throughput rate to lower command levels.

Objective Force would be much greater and more pervasive than the results discussed in Chapter 2 (see Table

A-2).

The SATCOM Terminal

The Army is developing a new satellite communications terminal to replace the canceled STAR-T (Super

High Frequency Triband Advanced Range Extension

Terminal) program. It has several candidates, including

a modified version of an existing SATCOM terminal

being used by the Air Force, called the Lightweight

Multiband Satellite Terminal (LMST), which operates

in the C-, X-, and Ku-band frequencies. Those frequencies, which in the order given provide increasingly

more bandwidth and increasingly lower probabilities of

interception and detection, collectively enable communications with most military and commercial satellites.

The Army expects that an improved version of the

LMST, available around 2006, will provide about

2.5 Mbps of operational throughput. By 2010, with the

addition of Ka-band capability, the terminal’s effective

throughput should be about 8 Mbps per channel.18 The

Army plans to buy 60 of these new satellite communications terminals at a cost of $195 million between

2003 and 2007.

18. Reported in Inside the Army, June 3, 2002, p. 1, and confirmed

by discussions with the Army staff on August 8, 2002. There are

Ku-band satellite terminals that generate such throughputs, but

the Ka frequency band offers the additional advantage of a low

probability of interception and detection.

B

Extrapolating Continuous-Flow

Information Across Command Levels

To justify its assumption that demand for communications bandwidth increases by a factor of three between

one level of command and the next higher level, the

Congressional Budget Office (CBO) used data from a

study conducted for the Army’s Communications and

Electronics Command (CECOM) in 2000 by the Mitre

Corporation.1 Table B-1 displays Mitre’s estimates of

bandwidth demand at the division, brigade, and battalion

command levels; the estimates exclude voice-only communications that are not digital and therefore not relevant

to CBO’s analysis. The relationships between the commands and the structure of the communications networks

associated with those estimates are assumed to exist

through 2010 except as noted in Chapter 2. In addition

to communications traffic associated with the operations

network, the estimates in Table B-1 include bandwidth

demand for intelligence data, fire-support data, and

network management. Because CBO’s analysis deals only

with bandwidth demand for the operations net, however,

those additional demands must be removed to facilitate

comparisons between the two sets of estimates (see

Table B-2).

The data in Table B-2 are consistent with CBO’s assumption that the demand for communications bandwidth

increases by a factor of three from one level of command

to the next higher level and decreases by a factor of three

at the next lower level. The data also indicate, however,

that this assumption is only approximately true—factors

somewhat higher or lower than three would also be consistent with the available data. Consequently, CBO has

considered the effects on the results presented in Chapters 1 and 2 of using either a factor of two or a factor of

four to extrapolate bandwidth demands to command levels

above and below that of the division (see Tables B-3 and

B-4 for a selection of these variations).

As the tables indicate, for extrapolations that use factors

ranging from two to four, significant shortfalls in the

supply of bandwidth are projected to occur at the brigade

and battalion levels today and at the corps and division

levels in 2010. The variations that are not presented (a

factor-of-four extrapolation of demand in 2003 and a

factor-of-two extrapolation for 2010) do not change those

qualitative results.

1. Yosry Barsoum, “Bandwidth Analysis (ACUS Only) of Division

Main, Maneuver Brigade TOC, and Tank Battalion” (briefing

prepared for the Army’s Communications and Electronic Command by the Mitre Corporation, February 29, 2000).

APPENDIX
38 THE ARMY’S BANDWIDTH BOTTLENECK

Table B-1.

Peak Bandwidth Demand at the Digitized Division, Brigade,

and Battalion Levels in 2003, by Mission

(In bits per second)

Mission Division TOC Brigade TOC Battalion TOC

Voice Communications 1,424,000 240,000 61,440

Maneuver 1,651,041 315,204 271,394

Fire Support 313,386 311,181 310,134

Intelligence and Electronic Warfare 2,570,327 1,364,168 283,763

Combat Service Support 297,118 128,158 0

Air Defense 30 197 100

Network Management 1,168,335 505,846 54,125

Total 7,424,237 2,864,754 980,956

Source: Congressional Budget Office based on briefing materials developed by the Mitre Corporation for the Army’s Communications and Electronics Command,

February 29, 2000.

Notes: The bandwidth demand detailed above is for the Amy Common User (communications system) and represents most of the operations net's trunk demand. However,

it excludes some older radios and walkie-talkies that, for the most part, support only local, nondigital voice communications that are not relevant to CBO’s

analysis.

TOC = tactical operations center.
APPENDIX B EXTRAPOLATING CONTINUOUS-FLOW INFORMATION ACROSS COMMAND LEVELS 39

Table B-2.

Peak Bandwidth Demand for the Operations Nets at the Digitized

Division, Brigade, and Battalion Levels in 2003, by Source of Demand

(In kilobits per second)

Source of Throughput Demand Division Brigade Battalion

Telephone 1,400 300 100

Army Battle Command System

Classified 300 to 1,000 300 30 to 100

Unclassified 100 to 300 100 0

Unmanned Aerial Vehicles 100 to 300 100 to 300 100 to 300

Video Teleconferencing 1,000 100 to 300 100 to 300

Total 2,900 to 4,000 900 to 1,300 330 to 800

Source: Congressional Budget Office.
40 THE ARMY’S BANDWIDTH BOTTLENECK

Table B-3.

Effective Bandwidth Supply Versus 

Peak Demand in 2003 Using a 

Factor-of-Two Extrapolation, 

by Command Level

(In kilobits per second)

Command Levela

Relative Supply

Versus Peak Demand 

(S : D)b,c

Corps 1 : 1.5 to 3

Division 1 : 5 to 8

Brigaded 1 : 1.5 to 38

1 : 20 to 309

Battalion 1 : 10 to 20

Company 1 : 4 to 6

Platoon 1 : 2 to 3

Squad/Vehicle 1 : 8 to 14

Source: Congressional Budget Office.

a. At the higher command levels, the table refers to the operations networks

only. At lower levels, the distinctions between the various communications

networks (for example, operations, intelligence, and fire-support) become

less clear.

b. Ranges have been extrapolated from the division level for the corps level

and for the company level and below. They have been rounded down to

the nearest power of three, which allows the demand per command level

to be distinguished while maintaining a conservative (lower) estimate of

the aggregate demand.

c. Based on an approximate logarithmic scale, the color coding is as follows:

yellow indicates that supply is between about one-third and three times

demand (a marginal demand/supply match), and orange signifies that

demand is approximately three to 10 times supply. Red(used here for the

lower brigade-level relationship and at the battalion level) means that

demand exceeds supply by a factor of 10 or more.

d. The up-arrow (8) indicates the throughput rate for communications to

equivalent or higher command levels. The down-arrow (9) indicates the

throughput rate to lower command levels.
APPENDIX B EXTRAPOLATING CONTINUOUS-FLOW INFORMATION ACROSS COMMAND LEVELS 41

Table B-4.

Effective Bandwidth Supply

Versus Peak Demand in 2010 

Using a Factor-of-Four Extrapolation,

by Command Level

Command Levela

Relative Supply

Versus Demand

(S : D)b

Corps 1 : 12 to 40

Division 1 : 10 to 30

Brigadec 1 : 2 to 68

1 : 4 to 109

Battalion 1 : 1 to 4

Company 3 to 4 : 1

Platoon 5 to 8 : 1

Squad/Vehicle 10 to 20 : 1

Source: Congressional Budget Office.

Note: Ranges have been extrapolated from the division level for the corps

level and for the company level and below. They have been rounded

down to the nearest power of three, which allows the demand per

command level to be distinguished while maintaining a conservative

(lower) estimate of the aggregate demand.

a. At the higher command levels, the table refers to the operations networks only. At lower levels, the distinctions between the various communications networks (for example, operations, intelligence, and firesupport) become less clear.

b. Based on an approximate logarithmic scale, the color coding is as follows: green (used here for the company, platoon, and squad/vehicle

relationships) means that supply is greater than demand by approximately a factor of three or more; yellow indicates that supply is between

about one-third and three times demand (a marginal demand/supply

match); light orange signifies that demand is approximately three times

supply; orange indicates that demand is approximately three to 10 times

supply; and red (used here for the corps and division relationships)

means that demand exceeds supply by a factor of 10 or more.

c. The up-arrow (8) indicates the throughput rate for communications to

equivalent or higher command levels. The down-arrow (9) indicates the

throughput rate to lower command levels.

C

Compressing Data to Reduce

Bandwidth Demand

Data compression has been suggested as a means

to reduce bandwidth demand. This Congressional Budget

Office (CBO) analysis concludes, however, that the most

likely effect of pending advances in data compression will

not be to empty saturated trunk communications lines.

Instead, those lines will probably remain saturated with

increasingly compressed data.

Data compression techniques differ depending on whether

or not some losses of data can be tolerated. If they can,

so-called lossy techniques may be used; if no losses may

occur, lossless techniques must be employed. The transmission of picture images (so-called imagery) or streams

of pictures (known as streaming video) can have some data

errors, on the order of a few percent, because the human

eye and brain unconsciously correct such anomalies. But

compression techniques that are used for transmitting

military orders, network management and other control

information, situation assessments, and much of the rest

of military data must be lossless.

A number of fast techniques exist for lossless compression,

but the prospects are small for major improvements by

2010 in the amount of compression such techniques can

achieve. The best one can obtain is about a 2:1 compression, on average, and military computer systems today

routinely employ such compression techniques for

transferring large data files. Computer users typically attain

lossless compression (and decompression) when they use

computer applications that zip, gzip, and unzip files.

Improvements on those techniques are being pursued, but

they usually involve the sequential application of known

techniques. Those techniques may produce improvements

of about 15 percent relative to current performance.

In contrast, substantial improvements in lossy compression

techniques will occur by 2010 because of an expected

reduction, by an additional order of magnitude, in the

transmitted data throughput. A key to that transition will

be the change from MPEG-2 to MPEG-4 standards for

data compression. (MPEG stands for Moving Picture

Experts Group.) Associated with each MPEG standard

is a different numerical algorithm. The MPEG-2 uses

numerical algorithms based on the fast Fourier transform,

which was optimized for computers about 40 years ago

to recast data associated with a stream of pixels—or more

properly, the pixel indices. (The data are recast as a properly weighted sum of trigonometric sines and cosines and

their higher harmonics, which are related to the second,

third, and higher powers of sines and cosines.) The trigonometric functions associated with the recasting are called

the basis functions. The fast Fourier transform exactly

evaluates multiplicative weights for each basis function

so that the weighted sum of the basis functions exactly

equals the original data when evaluated at the pixel indices.

In that sense, the weights replace the original data on a

one-for-one basis.

However, the mathematics of Fourier transforms proves

that smaller weights can often be ignored (set to zero)

while the remaining weights allow the original data stream

to be approximated to within acceptable error tolerances.

The ratio of the retained weights relative to the original

number of weights is the compression ratio. For typical

APPENDIX
44 THE ARMY’S BANDWIDTH BOTTLENECK

two-dimensional imagery and video, acceptable error levels

can be maintained by setting about nine-tenths of the

weights to zero. Therefore, under the MPEG-2 standard,

the retained weights for typical two-dimensional images

imply a data compression ratio of about 10:1. 

The new algorithm underlying the MPEG-4 is called the

wavelet transform. In addition to working with basis

functions like the sines and cosines noted above, it employs additional, specially tailored basis functions that

allow minimal errors with even fewer retained weights.

(In more metaphorical language, each basis function is

called a wavelet because graphs of some of them look like

waves.) Fast algorithms for employing the wavelet transform have been developed over the past 20 years. With

the MPEG-4 standard, typical data compression ratios

for two-dimensional images can often be expected to

improve to about 100:1.

In the military context, the Air Force expects to begin

using MPEG-4 data compression on a limited experimental basis in 2003, a move that would achieve an orderof-magnitude reduction in the bandwidth required for

transmitting video images collected by unmanned aerial

vehicles (UAVs). But rather than using the techniques to

reduce the total demand for bandwidth, the Air Force

plans to increase the resolution of the images transmitted

or the number of sensors (or both), which would result

in no net decrease in total bandwidth demand.1

 After the

effectiveness of UAVs in the recent Iraq and Afghanistan

campaigns, together with their novelty and the rapidly

changing doctrine for their employment by the Army,

there is no reason to expect that the Army will use these

data compression techniques differently.

Therefore, although improvements in data compression

will occur, CBO believes that in the future, the improvement will be used to keep the communications pipes full

of more and increasingly compressed data rather than

allowing the pipes to be emptied. Thus, improved data

compression is unlikely to affect the results of CBO’s

analysis regarding the 2010 mismatch between bandwidth

supply and demand on the battlefield.

1. Personal communication to the Congressional Budget Office from

Col. Rhys MacBeth, Commander, Digital Imagery Video Compression and Object Tracking Battlelab, Eglin Air Force Base, Florida,

August 10, 2002.
Glossary of Abbreviations

AAR after-action report

ABCS Army Battle Command System)

AFATDS Army Forward Artillery Tactical Data System

AMSAA Army Materiel Systems Analysis Activity

ASCII American Standard Code for Information Interchange

ATCCS Army Tactical Command and Control System

ATM asynchronous transfer mode

AWE advanced warfighting experiment

BLOS beyond line of sight

C2 command and control

C4 command, control, communications, and computers

CECOM Communications and Electronics Command

CSSCS Combat Service Support Control System

DAWE Division XXI Advanced Warfighting Experiment

DSL digital subscriber line

DSCS Defense Satellite Communications System

EPLRS Enhanced Position Location Reporting System

EPLRS (VHSIC) Enhanced Position Location Reporting System (Very High

Speed Integrated Circuit)

FBCB2 Force XXI Battle Command, Brigade and Below

FRAGO fragmentary order

FCS Future Combat Systems

Gbps gigabits per second

GCCS Global Command and Control System

HCLOS high-capacity line of sight

http hypertext transfer protocol
46 THE ARMY’S BANDWIDTH BOTTLENECK

ID infantry division

IDA Institute for Defense Analyses

IP Internet protocol

IT information technology

JTRS Joint Tactical Radio System

Kbps kilobits per second

LAN local area network

LMST Lightweight Multiband Satellite Terminal

LOS line of sight

LPD low probability of detection

LPI low probability of intercept

Mbps megabits per second

MIST Multiband Integrated Satellite Terminal

MPEG Moving Picture Experts Group

MSE mobile subscriber exchange

NTC National Training Center

NTDR Near-Term Data Radio

OPORD operational order

PCM pulse-coded modulation

SATCOM satellite communications

SDR software-defined radio

SINCGARS Single-Channel Ground and Airborne Radio System

SINCGARS (SIP) Single-Channel Ground and Airborne Radio System (System Improvement

Program)

SHF super high frequency

SMART-T Secure Mobile Anti-Jam Reliable Tactical-Terminal

STAR-T Super High Frequency Triband Advanced Range Extension Terminal

SUAV small unmanned aerial vehicle

TCP transmission control protocol

TOC tactical operations center

TUAV tactical unmanned aerial vehicle

UAV unmanned aerial vehicle

UTO unit task order

VTC video teleconferencing
GLOSSARY OF ABBREVIATIONS 47

WAN wide-area network

WIN-T Warfighter Information Network-Tactical

WNW wide-band network waveform




This publication and others by CBO

are available at the agency's Web site:

www.cbo.gov