The SDR technology evolution continues

3The Software-Defined Radio (SDR) concept is now a mature technology enabling radio functions to be defined in warfighters’ radios across the globe, not just in large government programs such as the Joint Tactical Radio System (JTRS).

Software- (SDR), a concept that first deployed with the General Dynamics Digital Modular Radio (DMR) system to the Navy in 1998, has become the de facto enabler of current and upcoming military radio designs. The ability to define radio functionality in software has enabled radio systems that can work with decades-old waveforms and new ones like the Soldier Radio Waveform (SRW). Many SDRs are already fielded by companies such as Harris RF in Melbourne, FL, while JTRS radios have entered full production. Future innovations will come from waveform and system developments.

“SDR technology continues to evolve,” says Lee Pucker, CEO of the Innovation Forum. “The SDR evolution occurred over the last decade, making it easier for radio manufacturers out there to do their jobs, getting new products deployed faster and enabling them to upgrade their radios while in the field. They just have to reprogram the functionality for new features. This solves big problems from the operational user and manufacturer perspectives.”

“We commissioned a study last year to size the market for SDR technology,” says Manuel Uhm, Vice President of Sales and Marketing at Coherent Logic and Chair of the User Requirements Committee of the Wireless Innovation Forum. “The study was done by an independent research firm, Mobile Experts. SDR technology is now prevalent in mobile terminals, mobile infrastructure, and public safety communications, as well as military communications.“

“The study shows pretty much every military radio has some form of SDR technology in it that’s been built in the last few years,” Pucker says. “SDR is pervasive everywhere. Our study found almost every commercial basestation uses SDR technology: 95 percent. For commercial handsets it is a different story, as they are disposable with only 50 percent using SDR.”

What’s next for SDR?

“Obviously the trends are toward smaller, lighter, and faster devices. Our customers demand bigger bit pipes to get more capability yet still be interoperable with their narrowband legacy equipment,” says Matt Nearpass, International Product Line Manager at Harris. “Next-generation radios still need the capability to work with waveforms that date back to pre-Vietnam and all the way up to the latest wideband waveforms. Generally the lifespan of a family of radios is about 15 to 20 years. We’re delivering additional capability on the same platforms because of SDR. It gives customers an insurance policy on the hardware platform they bought. We have to look ahead when developing radio platforms because not every waveform that will be used currently exists.”

One of the most popular SDR-capable systems from Harris is their Falcon III AN/PRC-117G radio, which is designed to host government waveforms. “It has a JTRS-SCA and is NSA Type 1 certified for information security,” Nearpass says. “The Falcon III leverages the SCA operating environment. We leverage the radios with SCA as an operating environment for international customers. It is the SDR nature of the radio that we’re utilizing, which makes it easy to roll out upgrades and new features.

“For SDR on the front end, the initial list of waveforms still remains the same – SRW, Wideband Networking Waveform (WNW), the Mobile User Objective System (MUOS), Tactical Targeting Network Technology (TTNT) – with not a lot changing or developing,” says Troy Brunk, Senior Director, Airborne Communication Products at Rockwell Collins in Cedar Rapids, IA. “The focus is on migrating those waveforms across a broader portfolio of products for all services – ground soldier platforms, air, and sea. The Rockwell Collins ARC-210 Gen5 radios use a Multi-Waveform Architecture – an optimized Software Communications Architecture (SCA) – and have the capability to host waveforms such as SRW and the MUOS (Figure 1).

21
Figure 1: The Rockwell Collins ARC-210 Gen5 radios use a Multi-Waveform Architecture, which is an optimized Software Communications Architecture (SCA).
(Click graphic to zoom by 1.9x)

“We also produce SDR technology internationally with a product called FlexNet.” Rockwell Collins fielded an SCA-compliant variant of that radio with a different security architecture. The JTRS waveforms were not exploitable, but the same basic protocols were developed to work with international waveforms. “Right now funding is the biggest constraint,” Brunk says. “However, radios are a large enough market to generate standards and protocols that drive interoperability across all platforms.”

“There are still limitations on many commercial SDR implementations,” Uhm says. “For example, while all 3G and 4G basestations are SDRs, many of them use hardware accelerators for computation-intensive functions such as turbo decoding for forward error correction. This limits the flexibility of the basestations since they are no longer future-proof at that point since the hardware accelerators cannot be upgraded in software. I believe processor technology is now advancing to the point where commercial radios can be fully software defined, including turbo decoding. This would enable SDRs to be fully virtualized where each new waveform is an application that can run on the hardware, even if the method of forward error correction is different.”

“Some of the things we see from the design side are on our ‘most wanted’ wireless innovation wish list,” Pucker says. Included was an improved certification process when it comes to third-party software. “A process that enables third-party software to be used across multiple platforms would significantly reduce development cost and speed up the time it takes to get a new waveform into the hands of the warfighter.”

“On the military side, interference mitigation is a key need for the warfighter, especially as tactical radios get jammed by other emitters for applications like electronic warfare and anti-IED,” Uhm says. “New equipment and algorithms for interference mitigation are critical to ensuring the warfighter can communicate at all times and receive actionable intelligence when needed.”

“Commercial technology helps us drive innovation to the tactical side,” Nearpass says. “However, we still don’t quite see civilian waveforms fully transitioning to the battlefield yet. Those networks still require a vast amount of infrastructure to provide that quality of service. On the battlefield you have to roll with your own infrastructure because it does not exist like it does back home and there are adversaries out there trying to disrupt communications. The waveforms must be made specific for military operations and threats, with dedicated military communications devices with military-specific encryption and anti-jam capabilities.”

SDR and JTRS

The JTRS program has been reorganized with the JTRS Joint Program Executive Office (JPEO) becoming the Joint Tactical Networking Center, responsible for managing SDR technology and waveform development within the DoD. The Handheld, Manpack, Small Form Fit (HMS) and the Airborne, Maritime, Fixed Station (AMF) will be run by the Army, while the Multifunctional Information Distribution System (MIDS) will be placed under Navy oversight.

Capability sought from the now-canceled Ground Mobile Radio (GMR) segment is being procured as a Non-Developmental Item (NDI) – the Mid-Tier Networking Vehicular Radio (MNVR). “MNVR will essentially meet the capabilities of the canceled GMR program, which was supplied by BAE Systems,” says John Byrnes, Director of Business Development at BAE Systems in Wayne, NJ. “MNVR will address the Army’s demand for a Mid-Tier Wideband Networking (MWN) capability, which provides an extension of data services from the upper tactical network at brigade and battalion levels to the lower tactical network at company and platoon platforms.”

A representative for General Dynamics, the prime contractor for the JTRS HMS family, says that two HMS radios, the AN/PRC-154 Rifleman radio and the two-channel AN/PRC-155 Manpack radio, will be part of the Army’s Capability Set 13, which is to be delivered to Infantry Brigade Combat Teams this fall. The HMS PRC-154 Rifleman radio uses the U.S. government’s SRW. The two-channel PRC-155 Manpack utilizes three government waveforms – SRW, WNW, and MUOS. It is interoperable with legacy radios so soldiers can use one channel for line-of-sight SINCGARS and SRW waveforms, while bridging to the second channel using the MUOS satellite system. Rockwell Collins and Thales are also part of the JTRS HMS team.

“As JTRS goes into production, a major focus is on volume production and cost reduction,” Uhm says. “This is an indication of the maturation of SDR technology. In many ways, SDR is now considered to be largely a solved problem, so technologies and tools that lead to even more efficient waveform and system development and lower SWaP-C are now desired, as opposed to basic enabling technologies. JTRS is essentially now a production program with very little funding for research and development. … This means that more effort will be spent on cost reducing JTRS radios. Unfortunately, it may also result in less innovation for the future.”

Managing SWaP

“In the military space, Size, Weight, Power, and Cost (SWaP-C) is still the major concern, with cost becoming a more important issue as JTRS radios go into production,” Uhm says. “Reducing the overall engineering cost of the program is critical to reduce the total cost of ownership of the program. Development productivity, at the waveform and system level, has a large impact on the overall engineering effort and cost and still needs improvement. Coherent Logix’s HyperX processor uses an ANSI C-based development environment to improve developer productivity compared to the use of specialized languages like , enabling the HyperX code to typically compile in a minute or two, allowing developers to perform multiple design iterations in a day.”

MIDS SWaP-C upgrades

Engineers at Solutions (DLS) – a joint venture between BAE Systems in Wayne, NJ, and Rockwell Collins in Cedar Rapids, IA – are providing the Link 16 capability with variants of the MIDS, including MIDS LVT and MIDS JTRS. “BAE Systems is the integrator of the MIDS and MIDS JTRS terminals. Rockwell Collins is the designer, developer, and manufacturer of the RF subsystems side of the terminal,” BAE Systems’ Byrnes says. “BAE Systems is responsible for the digital side, operating environment software, and waveforms for Link 16. There are several variants of MIDS that we are looking to reduce in SWaP-C upgrades – for land, air, and maritime domains.”

“DLS has developed a tactical Link 16 product with MIDS LVT and MIDS JTRS that reduces Size, Weight, and Power (SWaP) by designing a small form factor product in a conduction-cooled package that also will bring Link 16 to users who have not previously had access to this capability,” Rockwell Collins’ Brunk says (see Figure 2). “The reduced SWaP systems are needed for constrained space platforms such as Army helicopters and () – which are becoming a big focus in the military communications arena. Select users will also have the TTNT waveform on their systems.”

22
Figure 2: This image shows a Link 16 display as seen by a pilot. Photo courtesy of DLS
(Click graphic to zoom)

“Link 16 is unique because it is interoperable with the U.S. and coalition forces: To date, 38 countries use the technology,” Byrnes says. “The military wants to increase the capability of Link 16 bandwidth and users that can deploy, as it is a closed network waveform. Link 16 works the same, whether using a MIDS LVT or MIDS JTRS. Both of these terminal variants are undergoing changes to provide additional capabilities [and] be backward compatible and totally interoperable with every Link 16 system. The MIDS-LVT was developed to provide Link 16 capability at a lower weight, volume, and cost as a replacement to the legacy JTIDS terminal,” Byrnes says. “It enables real-time data communications, Ultra-High Frequency (UHF) and Line of Sight (LOS) situational awareness and navigation, digital voice and TACAN, in a crypto-secured, jam-resistant package.

“What we’re doing today on the LVT side is a block upgrade to the entire installed base incorporating crypto modernization of Link 16 encryption,” Byrnes continues. “Frequency Remap (FAA mandated) allows Link 16 carrier frequencies to be remapped to avoid interfering with other systems, and enhanced throughput to pack more information into Link 16 time slots. That will be an upgrade down the road. Industry will develop a kit or set of cards that will be installed on every terminal in service today to perform the upgrades. We are currently working the design and development that will be integrated into the terminals in the field in 2014/2015.

“The upgraded systems for the LVT Variant will not totally be SDR, but will have SDR capability as the new card will have much more software enabling more capability to be added without changing the hardware in future upgrades like on MIDS JTRS,” Byrnes says. “This will provide increased performance, producibility, and sustainability to ensure Link 16 through 2035. For the MIDS LVT SWaP modification, we redesigned and condensed all the card sets for the MIDS JTRS Terminal. This design change provided a new terminal with Link 16 capability on one channel and provides three additional new channels supporting expanding waveforms and capability in the same package. We also are working on enhancements to Link 16 itself to improve throughput and more.

“MIDS JTRS is an SDR and is more sophisticated than the LVT version,” he continues. “It is a four-channel terminal that includes Link 16 capability with the ability to incorporate additional networking waveforms as they become available. MIDS JTRS has jam-resistant capability, information distribution, position navigation, and mission management. On his terminal screen, a warfighter can tell who the good guys and bad guys are, where they are, and how they are moving. MIDS JTRS has now entered full rate production and fielding. Future MIDS JTRS upgrades will have Concurrent Multi-Netting (CMN), Concurrent Contention Receive (CCR). CMN enables the ability to receive as many as four Link 16 networks simultaneously while maintaining the ability to transmit on one Link 16 network. Warfighters would be able to operate in Link 16 on fighter networks, tanker networks, etc., no matter the tactical situation.”