Linking Warriors Across Land and Sea

New technology offers over-the-horizon networking for Marine expeditionary units.

An experimental communications system may soon connect U.S. Marine Corps units deployed on amphibious operations. Built using current satellite technology linked to radios and battlefield data management devices, the network will connect forward tactical units with task force commanders.

Littoral operations and new weapons such as enhanced cruise and antiship missiles make close-to-shore deployment of troops and equipment risky. A new doctrine called ship-to-objective maneuver (STOM) calls for forces to deploy and operate from over the horizon to deep inland, up to 200 nautical miles from a seaborne task force.

Linking and coordinating such widely dispersed units present another challenge. To provide connectivity for forces in next year’s SEA VIKING exercise, the Marine Corps Warfighting Laboratory, Quantico, Virginia, developed the expeditionary tactical communications system (ETCS). Based on the Iridium satellite constellation, ETCS will provide an over-the-horizon communications network that connects tactical units with commanders aboard ship.

Scheduled for the fall of 2004, SEA VIKING will test STOM principles under operational conditions. ETCS was developed as a short-term means to support communications for the event and, if successful, could immediately be put into operational use.

Developers originally considered a tiered architecture consisting of low- and high-altitude unmanned aerial vehicles (UAVs) and low- and medium-earth-orbiting satellites, explains Lt. Col. Nicholas Cusack, British Royal Marines, the Warfighting Laboratory’s command, control, communications and computer projects officer. The colonel is working at the laboratory as part of an officer exchange program. Col. Cusack believes the satellites are extremely important because they provide around-the-clock coverage regardless of weather conditions.

The UAV concept was discarded because of the large number of aircraft that would be required as communications nodes and the impracticality of basing them from an amphibious task force. “You’re not going to fly them from the sea base, not to the kinds of altitudes you require. You will have to have some kind of forward basing, which is limiting,” he observes.

Satellites, however, offer a wide-area view of the battlespace. “It gives you high look angles into difficult terrain that tactical warfighters will find themselves in—urban terrain with blockage from the skyline, complex jungle and mountainous terrain,” he explains.

Geostationary communications spacecraft proved unsuitable for connecting tactical units because they remain at a fixed point in the sky, usually low on the horizon. Troops engaged in combat often do not have the time or are not in the proper location to access these satellites. But large constellations in low to medium orbit were attractive because they provide nearly constant global coverage. “This is important because we’re looking at the tactical level where the guy on the ground is not interested in how he’s going to communicate—he’s interested in how he’s not going to get shot,” Col. Cusack maintains.

ETCS is based on a modified Iridium satellite communications system. It features a push-to-talk network capability necessary for a military command system instead of commercial dial-up, point-to-point links. A panel of Marine Corps experts determined that it was the only solution capable of supporting the experiment in the short time frame prior to the exercise. But the colonel emphasizes that ETCS is an experimental capability with limitations because of its commercial origins. Its major advantage is that it allows access to the 66-satellite Iridium constellation, which is a major U.S. Defense Department investment. Col. Cusack notes that the constellation has a global footprint and is a relatively low-risk technology for providing distributed voice and data communications across the battlespace.

Besides carrying voice messages, ETCS also moves data. Instead of a commercial Iridium data uplink, information is piggybacked over voice communications. The colonel explains that data transmissions will flow when the push-to-talk capability is not in use or in the pauses during a conversation. This is a necessity because of Iridium’s limited bandwidth.

But this technique offers an advantage. Col. Cusack points out that, even though the data pipes are small at 2.4 kilobits per second, they are still larger than the single channel ground and airborne radio system (SINCGARS)-based communications currently used by echelons below battalion. He is sanguine about ETCS’ ability to transmit enough essential information to support STOM. As envisioned, the system will maintain a common database to provide commanders with a shared tactical picture and transmit simple formatted messages such as calls for fire and logistics support. The system will not pass imagery or video data. Although ETCS can support limited imagery, it is not essential to the mission because other dedicated networks exist for this purpose, the colonel says.

Even within this bare-bones regime, managing a common tactical picture over such narrow channels is difficult. Col. Cusack shares that ETCS is assisted by another Warfighting Laboratory program called command and control integration (CCI), which is software designed to pass data efficiently through military communications networks’ limited bandwidth. With this software integrated into Marine Corps information systems, the colonel is confident that ETCS can help warfighters maintain situational awareness. He adds that CCI has already demonstrated this capability over SINCGARS networks, which have narrower bandwidth than Iridium.

All of the ships participating in sea viking will be equipped with ETCS systems. A major component will be 50 global network radios (GNR) linked to Marine Corps systems such as the intelligence operations server and the intelligence operations workstation aboard ship and in battalion combat operations centers, and data automated communications terminals (DACT) at the company level. 

ETCS uses an anchor radio to maintain GNR group channels and push-to-talk networks. A group radio controller device manages the system by receiving, duplicating and distributing voice and data packets to a Marine expeditionary unit’s different operational networks.

Units involved in sea viking will not require much new equipment, Col. Cusack shares. Most of the ETCS functions will work through the Marine Corps’ DACT devices. Information displayed on a company commander’s DACT is linked into an ETCS GNR and transmitted back to battalion or higher echelons. ETCS also will connect Marine Corps data systems within the Marine expeditionary unit’s command operations center. CCI manages this seamless flow of information. “That’s the real golden nugget, something really valuable that’s going to help the Marine Corps fuse system databases together to get a common picture,” the colonel explains.

SEA VIKING will determine how well these various technologies function under real operational conditions. Besides ETCS, a number of other systems will be tested. An ongoing series of technical assessments, simulations and wargames is taking place to test the new equipment. “Some of these technologies will undoubtedly fail. But unless you push the envelope to find out what’s good and bad, you never progress,” he says.

But the exercise cannot take place without a communications system capable of transmitting across long distances, the colonel maintains. ETCS was created to allow the doctrine to be tested in the field. Although the Marine Corps could have conducted a simulation using relays between major Marine bases to create an experimental network, the colonel notes that it would not have represented real operational situations.

Because ETCS is satellite-based, it eliminates the need to send communications personnel into a combat zone to set up relays and other equipment. This also maintains the Marine Corps’ tradition of agile, combat-oriented units. “We would like to get away from putting [communications] guys on the ground. All they do is communicate, eat food and need protection. The only guys that go on the ground are those with bayonets. That’s what STOM is all about,” he says.

Another major factor the experiment addresses is the lack of an existing communications system to direct STOM from a Marine expeditionary unit. A directive behind ETCS and its use of off-the-shelf technologies was for a system capable of deploying with a Marine expeditionary unit by 2005. Col. Cusack observes that modified Iridium may not be the final answer for STOM, but it will support sea viking and possibly other amphibious operations. “It’s useful now, and it is teaching us a few lessons. It can support our views on where we should be looking to invest in future military satellite communications for the tactical user,” he says.

Lessons learned from SEA VIKING will not only affect hardware choices for Marine expeditionary unit-based command and control systems, but also will influence Marine Corps doctrine, training and procurement.  “And it may be that this [ETCS] is perfect—we want something just like this with greater bandwidth. Or maybe it will be dreadful, and we don’t want to go down that path again. But the product is not just a material solution. It’s also knowledge of how to do and make things better in the future,” the colonel explains.