Modifications to very small aperture terminals will ensure secure battlefield communications
The military got one of its biggest security-related wake-up calls in many years in late 2009 when it learned that Iraqi insurgents were intercepting Predator transmissions by using easily available hardware.
Interception of transmissions is also possible with satellite communications that pass through very-small-aperture terminals, which has inspired extensive efforts to beef up what's commonly called transmission security (transec) for VSATs. The worry is that an adversary would be able to determine traffic patterns.
That vulnerability is not new, and it relates to the nature of communicating with satellites. Satellites beam their transmissions to a wide area so anyone in the proximity can intercept those transmissions. The technology to obfuscate satellite traffic patterns has existed for only the past couple of years.
“Without transec, it’s possible that for an adversary to tell who is talking to whom,” said Karl Fuchs, vice president of engineering at iDirect Government Technology. The company provides one of the key elements of military VSATs: the modem, which is where transec is housed. “In other words, is a lot of traffic going to Site A and very little traffic going to Site B, and then all of a sudden that changes and Site B is getting all the traffic? The adversary might not know exactly what’s going on, but they know something’s happening at Site B.”
Captured VSAT transmissions can also reveal the priority level of traffic. As in the example above, a sudden shift from low-priority transmissions to high-priority ones could alert an enemy about impending action.
One of the steps the military is taking to improve transec is transitioning from hardware key exchanges to software key exchanges.
“The key exchange is really the differentiator in what makes it easy or cumbersome for the end user,” Fuchs said. “The key to usability is the implementation of software key exchange as opposed to hardware key exchange. We are trying to help soldiers by extending this to the global network.”
The military also is working to make it easier to configure VSATs by addressing the IP configurations through which they communicate. The goal is to enhance worldwide portability so a VSAT configured in the United States can be deployed to Iraq, Afghanistan or any other part of the world and will operate as previously programmed with little to no user intervention.
“This means maintaining a persistent IP address from location to location to location around the globe,” Fuchs said. “That portability and usability is really what’s key to making this system effective for the end user. This is very much a modem challenge and, ultimately, an operator challenge because whoever owns the network has to design it with portability in mind.”
Programs of Record
The Army’s VSATs are managed by the Project Manger Warfighter Information Network-Tactical — part of the Program Executive Office for Command, Control, Communications-Tactical. PM WIN-T is perhaps best known for its communications-on-the-move program, but it also is responsible for all tactical military satellite communications terminals that the Army buys.
That includes tactical terminals for the Wideband Global Satcom (WGS) satellites, of which three are in orbit and three are under construction, and the Advanced Extremely High Frequency satellites, the first of which is expected to be launched in the fall. AEHF satellites will operate in the portion of spectrum that the military uses for protected, anti-jamming communications.
PM WIN-T manages a number of satcom terminal programs of record, one of which is being upgraded so it will be compatible with AEHF protected communications capabilities. That program is the Secure, Mobile, Anti-Jam, Reliable Tactical Terminal (SMART-T), which Raytheon built, and is in the field now, communicating via the older Milstar 2 satellite.
“We are waiting for the Air Force to finalize the control system for the AEHF satellites,” said Bill Anderson, director of satcom programs at PM WIN-T. “Once that happens and we can field that control system for our terminals, we will begin to retrofit those terminals. Hopefully, it will happen the latter part of this year.”
About 300 SMART-T extremely high-frequency units have been fielded, with about three-quarters going to Army Stryker Brigade Combat Teams and tactical command posts. The Defense Department, Air Force, Marine Corps and White House use the remaining units.
Data rates for current EHF units range from 75 bits/sec to 1,024 kilobits/sec, but those speeds will increase to about 8 megabits/sec on upgraded AEHF terminals.
The other major satellite terminal program of record within WIN-T is the Phoenix terminal. It is a quad-band terminal that operates in the military X and Ka bands via the older Defense Satellite Communications System and its replacement constellation, WGS. It also functions in the commercial C and Ku bands.
About 100 Phoenix terminals have been fielded so far — about 65 percent of the designated units — with many of them part of WIN-T Increment 1, which provides an at-the-halt communications capability, as opposed to Increment 2, which facilitates on-the-move communications. Phoenix provides communications support to Joint Task Force headquarters, Joint Force Land Component Command headquarters, Army Service Component Commander, and Army-level major subordinate command headquarters.
“Phoenix currently has the ability to transmit up to 20 megabits/sec per terminal, and the addition of a new modem will allow it to operate up to 50 megabits/sec,” Anderson said. “Not every terminal can operate at those high rates because you would use up too much satellite bandwidth. It is the warfighter’s call on how much data he needs at different places in his network.”
Phoenix is replacing the AN/TSC-85 satellite terminals, which only operate in the X band and have a throughput capacity of only 8 megabits/sec. Phoenix has two basic configurations: the AN/TSC-156A and AN/TSC-156B. The AN/TSC-156A is mounted on two Humvees. The first vehicle carries the entire electronics package while the second vehicle carries an integrated 10-kilowatt Tactical Quiet Generator and system spare parts. The AN/TSC-156B is also mounted on two Humvees but tows its generator in a trailer.