Tactical high-speed data network:
the Army’s interim answer to battlefield data transport

by LTC Brian Hamilton and MAJ Walton Brown

Under Army Vision 2010’s operational tenets, information superiority is the foundation of how we’ll fight in the future. Focused logistics, full-dimension protection, dominant maneuver and precision engagement hinge on our forces’ ability to pass information in a shared, timely and directed manner.

The objective is a command, control, communications and computers, intelligence, surveillance and reconnaissance network that adapts itself to the commander as his means to perform distributed command and control across a dispersed battlespace. The materiel-development community is fielding automated systems focused on Army Vision 2010’s goals. With these systems come an increase in information-exchange requirements, which translate into higher bandwidth demands.

The Warfighter Information Network-tactical is the solution to meet the Army Vision 2010 challenge, yet we don’t anticipate the reality of WIN-T until 2004 or later. In the meantime, the last 10 years have brought a tidalwave of bandwidth requirements to the battlefield that mirror increased demand in the commercial world. Signal units’ current primary fielded systems are suited to support the low-data requirements of the early 1990s.

This contention between demand and capacity has forced a multitude of ingenious unit solutions, yet these unit fixes are command-unique and change with each major deployment. The Army has recognized the critical need for a common data solution to serve as a bridge to WIN-T’s fielding. This realization spawned development of the tactical high-speed data network. This article serves to briefly describe the architecture, its capabilities and the characteristics of THSDN’s fielding.

In WIN-T’s absence, THSDN provides the Army’s interim solution to tactical data transport. With current and emerging battlefield data requirements unsatisfied by legacy systems, THSDN’s accelerated fielding will equip the Army, within resource constraints, with this solution over the next two years. THSDN provides a high-capacity data infrastructure to support diverse requirements, which include:

Army battle-command system;
Whiteboard collaborative planning;
Electronic mail;
Defense Message System;
Standard automated-management information systems across the three tiers of the combat-service-support data architecture;
Situation awareness;
Distributed databases; and
Other Internet-protocol-based data applications.

THSDN is fielded as an area common-user system enhancement that overlays a commercial-standard, IP-router network upon triservice-tactical and mobile-subscriber-equipment battlefield-communications systems. The Signal Regiment developed the architecture and successfully upgraded 82d Signal Battalion within one year, thanks to the efforts of Signal units worldwide, the Signal Center’s combat-developments directorate, Training and Doctrine Command’s systems manager for WIN-T, the program manager for WIN-T and the prime contractor for MSE/TRITAC systems.

History of data transport

MSE and TRITAC communications systems were fielded as voice C2 systems. Procured during the 1980s, these networks could satisfy their required 90 percent grade-of-service standards for voice communications and support data requirements via dial-up digital secure voice terminal 2.4 kilobits-per-second connections. Competing options and systems for data networks were simply not part of the original procurement of these systems due to cost considerations. The dawn of the 1990s spurred the introduction of the tactical-packet-network upgrade. Satisfactory at the time, TPN provided 16 kbs data support to small-extension-node-supported headquarters and 64 kbs connectivity between backbone-network switches. As users embraced commercial-off-the-shelf data and VTC applications, these data capacities were quickly overwhelmed.

Throughout the Signal Regiment, there stands a multitude of unit-produced solutions to tackle the challenge of evolving battlefield-data bandwidth requirements. With necessity as the mother of invention, these solutions have proven ingenious in supporting the warfighter’s C4ISR network needs. Many of these are solutions engineered with unit-procured devices such as high-speed multiplexer cards, Integrated Digital Network Exchange multiplexers or Codem TTI-1000 devices. Others are engineered with fielded FCC-100 first-level multiplexers or use data packages connected to tactical-satellite terminals to support point-of-presence servers, routers and VTC. Other unit solutions are more institutionalized and exploit commercial technologies bundled within tactical shelters, or provide commercial services on a fee-for-service basis per deployment.

While providing increased bandwidth, the numerous solutions share one feature: lack of commonality across the Army. This lack of commonality spans maintenance, spare parts, unit and resident training, network-management requirements, information-assurance features, router-configuration techniques and most importantly, universal connectivity across Army unit boundaries. Simply put, one unit’s data solution will not assure connectivity to its flanks or rear.

Genesis of a tactical data architecture

In December 1998 the Signal symposium’s council of colonels reviewed PM WIN-T’s proposed enhancement to MSE/TRITAC to provide improved data capacity across the Army. The system made use of an improved HSMUX card (figure below) at the extension switches. More importantly, it incorporated a developmental enhanced-trunk-group multiplexer orderwire (second figure below) card at the parent switch. This new capability at the parent switch was critical since it directed data to routers at the backbone-network level.

MSE/TRITAC improvements include improved HSMUX Improvements to the MSE/TRITAC system include an improved HSMUX card.
ETGMOW card added at parent switch To improve data capacity for the MSE/TRITAC system, a developmental ETGMOW card was added at the parent switch.

Previous uses of the HSMUX I card required static routing through the parent switching matrix, which proved cumbersome and engineering-intensive. In essence, HSMUX I cards, used by themselves, precluded speed of installation and flexibility of the standard database within MSE/TRITAC switches. The pairing of new-generation HSMUX II cards at the extension switches with the newly developed ETGMOW cards at the parent switches (with accompanying routers at both locations) proved to be a solution that would provide rapid installation of a high-bandwidth data network separate from the voice network. The resulting IP data network proves to be robust, survivable and – with THSDN’s integral forward-error-correction capability – resistant to throughput problems associated with noisy links.

As a result of the Signal symposium review, the council of colonels recommended that the Signal Center’s combat-developments directorate develop an Army-wide architecture to exploit the new capability within the available resources of about $55 million. This directive, combined with a short development window, set forth a partnership among the combat-developments directorate, PM WIN-T and field units to develop the best architectural fit for Active Component, National Guard and Army Reserve units. To publish an initial architecture in February 1999, the architects focused upon a 40 percent extension-node solution, with the priority of support targeted towards C2.

The TRITAC/MSE data-enhancement program became known as THSDN and was sent out to units worldwide for staffing and review. Also, the combat-developments directorate presented THSDN workshops at worldwide unit locations and various conferences to solicit field input. These inputs and consultation with PM WIN-T formed the basis for the final THSDN architecture and its accompanying network management and security architectures.

THSDN architecture capabilities

The foundation capabilities of THSDN rest within the configuration of the THSDN enhanced SEN. Within the communications modem, the HSMUX II card provides a first-level multiplexer that combines the standard SEN digital-transmission group supporting voice and TPN with up to four ports of digital data. The HSMUX II data is reformed via the high-speed FEC card and forwarded to the enhanced SEN’s router. The THSDN architecture pairs one HSMUX II card with one HSFEC card, which allows for two data ports, supporting up to 512 kbs of data per port.

To use all four ports of the HSMUX II, two HSFEC cards are required due to HSFEC’s two-port limitation. A typical THSDN SEN configuration can support 256 kbs MSE/TPN and 512 kbs of data. The increase in data capacity between a traditional SEN and a THSDN SEN is 32-fold – for example, 16 kbs vs. 512 kbs.

At the parent switch – whether a node-center switch, large extension node, forced-entry switch or TTC-39D – the IP router network is supported by the ETGMOW card. Before reaching the voice-switching matrix, the data serial is stripped off DTG, reformed via HSFEC and forwarded to the enhanced parent-switch router. Each ETGMOW card has two serial ports and is paired with a single HSFEC card for support of two incoming DTGs. Architects sized the parent-switch population of ETGMOW cards to support the accompanying 40 percent THSDN SEN fielding.

An internodal link from a THSDN-enhanced parent switch can support up to 3,072 kbs data, yet realize this depends on the transmission medium’s technical characteristics. Realistically, the upper-end data rates would be realized with cable, high-capacity commercial satellite or leased circuits.

If we follow the circuit flow from a SEN router to parent-switch router, the sequence is:

SEN router > HSFEC> HSMUXII> DTG over transmission> ETGMOW> HSFEC> parent-switch router

Once data arrives at the parent-switch router, the router configuration chooses the appropriate DTG for routing the data to its destination. This provides an IP-router network separate from the voice/TPN network. The THSDN network will still function during a switching-matrix crash.

Finally, the signal flow provides FEC at source and sink of each IP-router-network transmission link within the THSDN network. This capability is critical to support throughput within tactical networks that can often be noisy and experience marginal link bit-error rates.

THSDN supporting architectures

Net management of THSDN is developing as we field the first units. The main tools at the battalion and brigade S-3 sections are Cisco 2000 and Hewlett Packard’s Openview. Cisco 2000 provides configuration of the network’s routers, while Openview provides network topology and troubleshooting. Switch operators will boot their routers using a Personal Computer Memory Card International Association card initial configuration designed by network engineers. Once in system, the network-management cell can remotely reconfigure the router as necessary.

The training that accompanies THSDN will provide router basics to the operator while training more in-depth router configuration to system planners and engineers.

The THSDN security architecture – to include information-assurance functions – is planned but, for the most part, isn’t funded. Perimeter protection is done through the transportable-assemblage perimeter-protection package, which includes firewall and intrusion-detection functions. Inline network encryption devices allow tunneling of top-secret or sensitive-but-unclassified data through the secret system’s THSDN. At each router, a router-access control mechanism provides a software means for network security against intrusion. The brigade and battalion S-3 sections are responsible for monitoring and executing the IA mission.

THSDN training

THSDN training consists of two major areas: new-equipment training and resident training. NET will occur in conjunction with the equipment’s fielding and is anticipated to take five weeks. This training period presents a challenge to unit training schedules, especially those of National Guard and Reserve units.

NET covers router management, network planning and switch-operator functions, and culminates with a three-day network exercise.

Resident-training sites at the Signal Center will receive THSDN equipment halfway through the fielding cycle. The upgraded Signal curriculum will provide THSDN-trained operators and network managers to units in the field. This will be accomplished through classroom instruction, hands-on equipment operation, computer-based training and creation of a router laboratory.

Objective architecture

Discussed thus far, the THSDN architecture provides a fielding template that upgrades about 40 percent of the Army’s SENs. When faced with fiscal realities of limited resources, the THSDN fielding architecture is a constrained view that provides the best Army fit within available funding. The objective architecture that accompanied this effort produced a 100 percent THSDN solution at both the parent and extension switches. With TPN’s limited bandwidth, the objective architecture is justified by the information-exchange requirements for tactical-operations centers under both Army of Excellence and Force XXI categories.

See figure below for Force XXI THSDN architecture.

Force XXI THSDN architecture Force XXI THSDN architecture.

One main benefit of the THSDN fielding is that it’s a type-classified Army system, so units are free to procure more THSDN capability using unit or other-source funding. The cost of upgrading a SEN is about $25,000 at the time of unit fielding.

Also, the total number of THSDN-enhanced SENs needs to be paired with a proportionate increase in ETGMOW capability at the unit’s parent switches. Upgrading a unit’s THSDN capability during initial fielding reduces equipment and training costs and minimizes disruptions of the unit’s training schedule. In 82d Signal Battalion’s case, through division and corps sources, the unit upgraded its battalion to a 100 percent solution.

As a final note for units who’ve invested in HSMUX I cards, these cards are fully compatible with THSDN at their manufactured data rate of 256 kbs, half that of the improved HSMUX II card.


The increase in data bandwidth requirements over the past 10 years, paired with the data demands of future systems, presents a severe shortfall in the data capacity of our legacy field systems. At the unit level, commanders have exercised initiative and ingenuity to solve these problems, yet their solutions don’t guarantee connectivity with their rear and flank units. Their solutions aren’t common across the Army.

Objectively, WIN-T will provide the common solution to satisfy the warfighter’s future battlefield-network-support needs. Until then, THSDN serves as the Army solution for increased data capacity on today’s battlefield to meet the challenge of the user’s requirements. Also, THSDN removes the unit’s distraction of searching for data solutions and allows them to focus their fiscal and intellectual resources on their wartime mission. THSDN is neither a replacement nor surrogate for WIN-T, yet it provides an excellent interim answer to the critical void of data transport existing within MSE/TRITAC networks.

LTC Hamilton serves as chief of the concepts and architecture division in the combat-developments directorate at the Signal Center, Fort Gordon, Ga. His previous assignments include S-3 of 440th Signal Battalion (Task Force Eagle, Bosnia-Herzegovina); assistant S-3, 22d Signal Brigade; commander, Company A, 67th Signal Battalion (Operation Desert Shield/Storm) and platoon leader/operations officer, 72d Signal Battalion. He previously served in combat developments and participated in the Training with Industry program within GTE’s MSE division. He holds a master’s of science degree in decision information systems from Arizona State University and a bachelor’s of business administration from University of Texas at El Paso.

MAJ Brown is chief of the systems-architecture branch in the Signal Center’s combat-developments directorate. His previous assignments include brigade Signal officer for 470th Military Intelligence Brigade; commander, 69th Signal Company; operations officer, 40th Signal Battalion; and executive officer, 521st and 209th Signal Companies. He holds a bachelor’s of science degree in electrical engineering from Clemson University and participated in the Training with Industry program at TRW.

Acronym QuickScan
C2 – command and control
C4ISR – command, control, communications and computers intelligence, surveillance and reconnaissance
DTG – digital-transmission group
ETGMOW – enhanced-trunk-group multiplexer orderwire
FEC – forward-error correction
HSFEC – high-speed forward-error correction
HSMUX – high-speed multiplexer
IA – information assurance
IP – Internet protocol
Kbs – kilobits per second
MSE – mobile-subscriber equipment
NET – new-equipment training
PM – program manager
SEN – small extension node
THSDN – tactical high-speed data network
TPN – tactical-packet network
TRITAC – triservice tactical
VTC – videoteleconference(ing)
WIN-T – Warfighter Information Network-tactical

dividing rule

Back issues on-line | "Most requested" articles | Article search | Subscriptions | Writer's guide

Army Communicator is part of Regimental Division, a division of Office Chief of Signal.

This is an offical U.S. Army Site |
This is an offical U.S. Army Site |