Supporting Real-Time Warfare with Link 16: Sponsored Content
The Link 16 tactical data link has connected warfighters since the 1980s. But while the system is still associated with supporting large platforms such as aircraft and ships, it is now increasingly being used on the ground by smaller vehicles and dismounted troops to connect forces together into secure, ad-hoc networks capable of supporting a variety of missions.
Link 16 began as a Cold War command and control system to connect U.S. and NATO F-15 jet fighters to the long-range radar picture provided by airborne early warning and control (AWACS) aircraft to intercept incoming Soviet planes in an air battle over Western Europe. Designed before the introduction of satellite-based global positioning system (GPS) and intended to work in a combat environment with intense radio frequency (RF) interference and jamming, the data link was designed to be robust and to have its own navigation capabilities, says Andy Kessler, vice president and business area director for next generation tactical data links at Viasat Inc.
Early Link 16 terminals were refrigerator-size racks that weighed 300 pounds. This originally restricted the system to being installed on large command and control platforms, such as AWACS aircraft and warships. However, with advances in technology the latest Link 16 terminals are as compact as a paperback book and about two pounds in weight. With terminals this small and light, Kessler notes that there are many more platforms that can now access the Link 16 network.
The ongoing development in technology is important because it helps the U.S. military answer a longstanding operational problem encountered in Joint missions: coordinating air and ground forces for close air support. Handheld Link 16 terminals, like Viasat’s Battlefield Awareness and Targeting System-Dismounted (BATS-D), were initially developed to solve some of the inherent problems with close air support in a COIN environment, such as the delay between requesting air support and receiving it from aircraft overhead, and avoiding the risk of accidental fratricide that was prevalent in such operations.
Another advantage of using Link 16 for dismounted COIN and conventional military operations is due to what Kessler calls the network effect: the system’s architecture allows nodes to automatically connect to and leave the network as they need. The U.S. close air support aircraft are already equipped with Link 16 terminals, plugging them into the airborne and theater-wide network. By putting a terminal in the hands of a Joint Terminal Attack Controller (JTAC), this allows units on the ground to directly communicate with close air support platforms.
However, the opposition in COIN operations rarely has any anti-air defenses nor does it have the jamming capabilities that a near-peer adversary would have. Over nearly two decades of COIN operations, this meant that the U.S. and coalition allies could rely on many transport layer waveforms that weren’t designed for a contested RF environment.
“That’s a problem,” Kessler says.
One of the advantages of Link 16 is that its inherent robustness lets commanders build up the resiliency of their tactical networks as part of their Primary Alternate Contingency Emergency (PACE) communications plan for operating in a contested RF environment—something the Department of Defense expects to be the norm in any future conflict with a near-peer adversary.
Robust Design
Another advantage of Link 16 is built into its design. Link 16 isn’t just a transport layer, it also includes a message set and established “business rules” for the execution of real-time warfare that requires units to have situational awareness, transactions for command and control, target designation, and assignment and engagement designations, says Jon Stearn, chief technology officer for Viasat’s next generation tactical data links division.
“There’s a very good rule book of ‘Hey, here’s how we communicate when someone gives you an order, or here’s how you acknowledge it, that’s built into Link 16.’ So when platforms implement Link 16, they get to leverage that framework,” Stearn explains. He adds that when the rule book was originally created during the Cold War, while much of it describes and supports air-war operations, there is also a surface and ground war component.
The Air Force and Navy were the original adopters of Link 16, so traditionally there was more employment for air-to-air and surface-to-air missions, particularly from the Navy’s standpoint, notes Stearn. Much of the U.S. military’s focus for Link 16 has traditionally been for units tasked with air superiority and battle group-centric operations for the Navy connecting multiple surface ships and an aircraft carrier’s air wing.
But the Link 16 rule book also has ground operational material, such as repromulgation relay, which Stearn describes as “an almost MANET-style implementation that’s available in Link 16 that has not previously been used because there weren’t a lot of ground units needing that capability.”
Real-Time Warfare
What Link 16 is designed for is real-time warfare, which is substantially different from current operations.
The last 17 years of COIN-based warfare, where drones and other aircraft could safely orbit a battlefield, observing operations below, led to the development and extensive use of streaming video. But fighting an equal or near-equal peer with dedicated air defenses and electronic warfare capabilities means that it will be more challenging to have persistent video streams of a potential target.
Link 16 is designed to deliver actionable information to warfighting entities to make operational decisions based upon the situational awareness it provides as well as its utility as a command and control link. Link 16 isn’t designed for high bandwidth video streaming. Even though the system uses a relatively wide swath of the frequency spectrum, it trades data rate for robustness. This was an intentional tradeoff, Stearn says.
“You’re going to have to make real-time decisions based on fused tactical data, not as much by operators looking at a video feed,” Stearn explains. “So that’s what Link 16 was designed and built to do and what it’s done for many years. With the technology advancements, we’ve really been able to introduce more platforms, more players, and bring more active participants into a network.”
One example of this is Viasat’s BATS-D, which was designed for use by dismounted warfighters. BATS-D was developed to address a capability gap—providing ground units with a direct digital connection to close support aircraft to speed engagements and to reduce fratricide incidents.
According to Kessler, there are other on-the-ground uses for Link 16, such as calls for artillery support, where the same principles for speed of engagement and deconflicting blue-on-blue incidents apply and can be done on the same network and transport layer, but for a different mission.
This is also very helpful in any potential conflict with a near-peer adversary where the RF environment is contested. Link 16’s transport layer can operate in such conditions and support command and control to ground forces needing to operate and communicate amongst themselves that have little to do with supporting aircraft, Kessler explains.
Links and Bubbles
From the 1980s and through the 2000s, Link 16 was primarily used at the Navy battle group or Air Force theater level. But as the 2000s progressed, the network was extended from airborne platforms to support a variety of other operations. In Southwest and Central Asia, much of the military’s information uses the Joint Range Extension Application Protocol (JREAP) across IP communication links leveraging the “business rules”
of Link 16, Stearn says.
However as the DOD changes its operational stance, Stearn sees future Link 16 networks as a series of “bubbles” containing a variety of tactical nodes connected to a gateway with a big data pipe back to the theater network or continental U.S.-based headquarters. These bubbles can be anywhere from 10 to 200 miles in range, depending on the use and the platforms serviced. In such future configurations, Link 16 will bridge the network’s edge linking warfighters to a gateway, as opposed to the traditional arrangement of a theater-wide Link 16 bubble, he explains.
Stearn views Link 16 as a “last hop” for secure communications in an RF challenged environment because of its robust architecture and its ability to form ad-hoc networks. It also benefits from using Type 1 encryption to protect users on the network. The communications bubbles can be expanded and then be collapsed down to fewer users afterwards depending upon the real-time operational needs.
“I think you’ll see a lot more of these dynamic Link 16 bubbles stand up. If none of the local platforms have access to a backhaul network, the local bubble is going to get bigger to support more platforms and cover a larger geographic area. When some of the platforms have access to a high speed backhaul, those platforms can share that access via Link 16 to the local users,” explains Stearn.
Because the U.S. and its allies had complete air dominance in Southwest and Central Asia, coalition forces had the luxury of essentially uninterrupted communications, Kessler says. This also meant that the U.S. also had the time to build up forces in a specific location.
However, in a peer-to-peer or near-peer conflict, the assumption is that the U.S. and its allies will enjoy none of these advantages and instead make use of temporary air superiority in a given time and location while communications of all kinds will be constantly challenged. The overall tempo of action will also be significantly increased.
When an adversary contests communications, commanders need to have a PACE plan for line-of-sight and beyond-line-of-sight links. Kessler says Link 16 can do this by providing secure access to a gateway via a communications bubble. It is important to provide as many pathways as possible to get information to warfighters.
“We need to have more arrows in our communications quiver to make sure that we can maximize the likelihood of being able to get a message in or out when the adversary is challenging all of them,” notes Kessler.
