Tackling RF-Denied Environments

Mar 9, 2017

For more than a decade, the U.S. Army has been moving at an accelerated pace to modernize its warfighting capabilities in the face of budget constraints. Regarding radios, the Army has laid the foundation of its network and has been using a combination of large-scale programs, such as the Warfighter Information Network-Tactical or WIN-T, and individual purchases of technology, like the HMS Manpack, to provide Soldiers with secure and robust communication of voice and data to virtually any domain.

Modernization sometimes comes with a cost. In this case, overreliance on one radio capability can cause a single point of failure. Interference and RF-denied environments are probably the greatest threats that our warfighters face today and the most difficult requirement to plan. As the services look at how to conduct successful operations in an increasingly RF-denied environment, tools that have worked in the past should be at the forefront of a redundant and resilient strategy.

There is no silver bullet for denied satellite and no one technology that should be relied upon. 

The services need a layered defense with a robust ecosystem of communications capabilities that include radios and corresponding waveforms. Adversaries have shown their cards and we need to take them at their word that they aim to disrupt our communications.

An example of one technology that’s coming back into fashion and providing an additional layer of resiliency is the high frequency (HF) radio. The good news for users is that this radio isn’t your grandparents’ radio. The capabilities within have eclipsed HF radios of past and offer a robust complement to satellite communication (SATCOM) radios. There’s no mistake why industry has continued to innovate on this stalwart technology.

Regardless of where the U.S. operates, there will always be spectrum allocation that the HF radio can use globally. Additionally, there is an automatic link establishment, so users won’t have to figure out if the frequency is going to have interference. One of the most difficult aspects of waveforms is establishing the link and coordinating the channel among the users. HF doesn’t automatically fix those issues, there is still some art to it, but in terms of cognitive radios that seamlessly coordinate and configure the user group, HF is pretty close to making this a science. Most importantly, HF radios offer Type 1 crypto architecture for Top Secret and below communications.

Just as with any technology, there should be repetitive use and training on all of these systems and it should be done together in concert. Industry continues to push forward on the ad hoc abilities of the waveforms, but nothing replaces the value of training.

Innovation on the old shouldn’t mean ignoring the new. There is no question about the value of SATCOM and its role in beyond-line-of-sight (BLOS) operations. Operating in harsh, bandwidth austere environments without a line-of-sight to base, conventional radios cannot cope with the enormous bandwidth required to transfer the high-resolution imagery and video that saturate the modern battlefield. SATCOM can provide that critical link between warfighter and base. Waveforms for SATCOM have revolutionized battlefield communications.

As I discussed back in May, the Mobile User Objective System (MUOS) program, and its waveform, continues to make progress and will be the leading SATCOM waveform available. Many radios today are ready to integrate the waveform with the mere download of the software. But, just as with any technology, we cannot and should not develop an overreliance on it. Waveforms, and the radios, only work if they can transmit and receive. The most successful military operations involve an interconnected web of tactics, technologies and capabilities. The author of this article from the Marine Corps Gazette captures the issue well: “Essentially the loss or degradation of the space layer means possibly fighting with sand in our eyes or, worse, completely blind.”

Why Waveforms?

One of the questions I’m frequently asked concerns waveforms and the abundance of them in today’s radios.  Why can’t the same one be used across all platforms and what makes each of them unique?

To fully answer these questions, I think it’s important to go through a short history lesson of waveforms—how and why they came to be and the importance of setting the right requirements for the waveform, especially in the RF-denied environments our warfighters face today.

The rise of the waveform began in the 1980’s as software-defined radios (SDR) became the cutting-edge technology of the tactical radio world. Unlike radios of old that relied solely on radio waves in a limited band of spectrum, SDR allowed users to tap into more of the electromagnetic spectrum, but to do this you need waveforms to communicate. A waveform encompasses everything that is used to transmit and receive over the air: electromagnetic settings; forward error connection; protocols; data encryption; security; and the list goes on.

As users adopted SDRs, the technology was integrated into platforms across the services, from satellites to aircraft to ships to tactical handheld radios. Not all waveforms are created equal in the platforms as there is no steady state. For example, waveforms in aircraft have to be able to travel quicker than in ground radios, per se. Additionally, the services aren’t keen on refreshing equipment as quickly as technology in radios can upgrade, and with the lifecycle of aircraft and ship platforms nearing 50-plus years, many platforms run on older waveforms. To give you an idea of how many waveforms exist, Harris has more than 70 waveforms in its library. A standard radio is typically loaded with between 10-20 waveforms.

To continue with forward progress in radio evolution and to win in RF-denied environments, planners need to take two things into consideration in regards to waveforms, interoperability and requirements. Interoperability needs to be explored both between coalition forces as well as interoperability between platforms, many of which run legacy waveforms. Two-channel radios are making it increasingly easier to ensure interoperability.

The Army’s network foundation currently includes connecting airborne, dismounted, vehicular and space-based assets using interoperable waveforms such as SRW, WNW, and MUOS which enables global connectivity. This integrated communications capability may soon provide higher levels of interoperability with the other services including SOCOM, the Marine Corps and Air Force. As we march forward into the future, we must remember the lessons of the past and why resiliency matters.  

This article first appeared in C4ISRNET.