Expanding Link 16's Reach Through Concurrent Multiple Reception (Sponsored Content)

May 1, 2019
By Henry S. Kenyon

Multichannel systems provide tactical units with data link capabilities, enhanced connectivity.

From the end of the Cold War to the present era, there has been a growing need for military platforms to coordinate for operations and to share information. The Link 16 family of data links has been central to providing critical battlefield information to the U.S. and its allies since the 1980s.

But Link 16 has primarily been used for theater-wide operations, connecting fast jets and large platforms like ships. One area where the data link has not seen much use was in tactical missions on the ground connecting helicopters, ground vehicles and dismounted troops.

The Department of Defense (DOD) has spent the last decade investing heavily in a variety of Link 16 applications for tactical operations. An important part of this research has been to alleviate the limitations on current Link 16 networks, and a key aspect of this is the ability to receive multiple messages in a single time slot, says Andy Kessler, vice president and business area director with Viasat Inc.

Legacy Link 16 radios were traditionally only capable of receiving one message at a time on a single channel. This was effective for fighter jets receiving targeting information from airborne warning and control system (AWACS) or Joint Surveillance and Target Attack Radar System (JSTARS) aircraft to warships sharing information, but as more platforms have sought access to that information, it has strained the capacity of the theater net.

One way to improve this awareness and mitigate network capacity challenges is through concurrent multiple reception (CMR), a capability that allows Link 16 radios to receive up to four separate messages simultaneously. By receiving information across four channels simultaneously, it allows radios to use fewer time slots on the network, which is easier on the overall network and saves bandwidth and is important for smaller terminals, says Pete Camana, the chief engineer for Viasat’s Tactical Data Links Group.

Upgrading an entire family of radios

Viasat was aware of the DOD’s Link 16 requirements for next-generation tactical data links and took steps to modify its portfolio of tactical radios to meet those needs, Kessler says. The company integrated Link 16 advances, specifically CMR capabilities, into its existing line of Link 16-capable radios. These features, coupled with the Link 16 Enhanced Throughput modes that were already resident in Viasat’s next-generation products, will enable network planners to fully optimize network performance enabling maximum participants sharing maximum capacity of information to support mission requirements.

The latest version to have the advanced Link 16 CMR capability is the KOR-24A Small Tactical Terminal (STT). Over 1,400 units have been fielded by the U.S. military and its allies, Kessler says. Viasat also upgraded its AN/PRC-161 Battlefield Awareness Targeting System (BATS-D) handheld Link 16 radio. These new capabilities are also included in the company’s Move out/Jump off (MOJO) expeditionary tactical gateway system.

Viasat is the only industry firm to have a commercially available handheld Link 16 system, Kessler maintains. While other companies have Link 16 capabilities associated with various DOD programs, he notes that Viasat approaches the Link 16 market with a more commercial mindset. He explains that many other firms react to government requirements when they are released in a formal request for proposal, rather than creating a capability based on anticipated market demand.

One of the engineering challenges of moving Link 16 from aircraft to small handheld units was miniaturization, Camana explains. Part of this size reduction is attributable to the extensive use of field programmable gate arrays (FPGA’s) and other programmable devices in the radios’ architecture.

However, the major cost reduction was in reducing the price of the transmitter. Link 16 transmitters are very complex and require a lot of power. By reducing overall power consumption, much of the cost of the transmitters was cut, Camana says. He notes that airborne Link 16 systems have transmitters that typically use 200 watts during peak transmission time.

High-power messages are important for aircraft and large platforms that must get targeting and other data out through jamming and other types of radio frequency interference, Camana says. The major difference between these types of systems and small, tactical Link 16 units is that the small units tend to receive more than they transmit. By comparison, he notes that the transmitter in the company’s small tactical handheld only uses 8 watts.

Kessler attributes some of this advantage to Viasat’s approach to product development. Technologically, the company’s engineers work with available systems and software to come up with novel solutions. But the other facet of this approach couples this engineering methodology with personnel who have military operational backgrounds and represent the user community to help identify capability gaps, he explains.

One lesson learned developing the handheld Link 16 BATS-D radio was that while Viasat’s engineers knew they could make a small Link 16 radio, what was missing was the specific mission/problem that needed to be solved.

“We weren’t doing it in the manner that was best suited for the market until we understood that the application was to rapidly support a close air support mission based on a direct digital connection between the JTAC [joint terminal attack controller] and the pilot of the aircraft,” Kessler said.

Besides getting feedback from the user community, Kessler says Viasat was able to use agile, rapid prototyping techniques to test systems in operational and “quasi-operational” environments. He notes that the BATS-D radio went from concept to initial user tests in slightly less than 18 months followed by product certification and initial fielding nine months after that. This is compared to a formal DOD program, which can average about 10 years, he says.

Machine-speed operations

One of the main uses for handheld Link 16 systems at the tactical level is to coordinate close air support operations. The digital connection through the data link greatly improves coordinating close air support and greatly reduces the possibility of blue-on-blue incidents on chaotic battlefields, which historically have been a danger of close air support operations since World War II.

The data links connecting the dismounted JTAC and the aircraft overhead provide rapid two-way data connectivity/communications and integrates the controller as a “friendly” symbol on the pilot’s situational awareness display. If the pilot has a helmet-mounted cueing system, they could look out of their cockpit windows and see, via augmented reality, the exact location of the JTAC on the ground, Kessler explains.

Link 16 allows the JTAC on the ground to designate the exact target they want attacked into the aircraft’s mission computers. This is done directly via machine-to-machine communication, greatly accelerating the speed of the air support request and the resulting action by the aircraft. This is a great improvement over the traditional Nine Line air support process in which the JTAC uses nine different phrases, passed via voice communications, to identify themselves and the target to the supporting aircraft.

“By having the JTAC with a handheld Link 16 transmitting accurate data to a close air support aircraft that already has Link 16, you’re really accelerating the speed of engagement and you’re significantly reducing the fog of war,” Kessler says.

The machine-to-machine communications between the JTAC’s handheld Link 16 system and the ground support aircraft’s take seconds. This means that a JTAC coordinating an attack with an incoming F-15 can be done quickly and efficiently within 10 seconds, rather than multiple minutes, Camana says. The JTAC can also designate multiple targets, so as fast as the jet can make an attack pass, a new target can be designated and lined up.

“All of that gives the pilots much more confidence and gives the JTACs more confidence in overall mission effectiveness and warfighter safety,” Camana says.

Besides its family of Link 16 radios, the next area of development Viasat is considering is embedded Link 16. Camana explains that this covers a variety of smaller platforms such as unmanned aerial systems (UAS), weapons and other autonomous systems. Such systems could operate independently, dispersed across a battlefield collecting intelligence and then swarming together to destroy or neutralize a target. The company already has several contracts to install Link 16 systems on unmanned platforms and weapons, he says.

Visit viasat.com/cmr for more information.

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