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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 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), CBO has estimated the bandwidth that the JTRS, WIN-T, and MIST programs will provide at all levels of command (see Table 10).
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 1,100
Battalion 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 fire-support) 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 (↑ ) indicates the throughput rate for communications to equivalent or higher command levels. The down-arrow (↓ ) indicates the throughput rate to lower command levels.


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 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)
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   1b   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.

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.

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 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).
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 fire-support) 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 right-hand column (TUAVs are networked) would apply.

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 high-capacity 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 net-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).
Table 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 10
  1 : 5 to 15
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 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 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 (↑ ) indicates the throughput rate for communications to equivalent or higher command levels. The down-arrow (↓ ) indicates the throughput rate to lower command levels.

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)

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.
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.
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.
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.
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.

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