SDR tech deployed throughout military, but design challenges remain

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September 29, 2016

Every month the McHale Report will host an online roundtable with experts from the defense electronics industry ? from major prime contractors to defense component suppliers. Each roundtable will explore topics important to the military embedded electronics market. This month we cover software defined radio (SDR) technology and its current use in the military electronics market and its future outlook.

This month’s panelists are: Manuel Uhm, Director of Marketing, Ettus Research, a National Instruments company and Chair of the Board of Directors of the Wireless Innovation Forum (formerly the SDR Forum); Stephanie Chiao, Product Marketing Manager, Per Vices Corp.; John McHale, Group Editorial Director with Military Embedded Systems and Proprietor of the McHale Report.

MCHALE REPORT: Many say SDR is a solved problem as far as the military is concerned. If so, then what is the state of deployment for SDR in military applications? How ubiquitous has it become?

UHM: SDR, as defined by the Wireless Innovation Forum, is a radio in which some or all of the physical layer functions are software defined. Based on this definition, SDR is unquestionably the dominant radio technology from military radios to satellite communications (SATCOM) to mobile phones. Specifically with respect to military applications, every current tactical radio, signals intelligence (SIGINT), electronic warfare (EW), and radar system uses some type of programmable processor(s) to do the baseband processing, typically FPGAs and general-purpose processors (GPPs).

CHIAO: Technological advances have certainly allowed SDR technology to find considerable application within the military. A number of traditional radio applications, including radar, radio communications, and some electronic warfare applications have seen the introduction of platforms that make extensive use of SDR.

However, SDR technology is best viewed as a tool that can help address some significant challenges unique to modern warfare. This includes sensor integration, signals intelligence and data communications, navigation and guidance, and supporting electronic superiority. More fundamentally, we still haven’t seen SDR platforms capable of consolidating traditionally disparate applications onto a single platform, as we’ve come to expect from software running on commodity computers. Within this context, it’s not at all clear that SDR is a solved problem - and might even suggest that a broader, more comprehensive, approach is needed to successfully benefit from the advantages this technology provides.

MCHALE: While you may not get consensus from the industry that SDR is a “solved problem,” it’s been successfully deployed within the military for decades with arguably the first military SDR being the Digital Modular Radio (DMR) from General Dynamics that was used on Navy platforms. And while the Joint tactical Radio System (JTRS) suffered from many technical and non-technical challenges, its essential blueprint and the Software Communications Architecture (SCA) have enabled companies like Harris, Thales, Rockwell Collins, and others to field SDR-enabled devices with warfighters across the globe. They can all handle multiple waveforms, but many in the industry say the SDR platform that could handle any and all waveforms and be used for any mission remains far off.

MCHALE REPORT: Despite the proliferation of SDR products among warfighters such as the Harris Falcon family and the Flexnet solutions from Thales, some say switching simultaneously between waveforms with small radios is not as easy as once thought and that problems exist that still need to be overcome. That said what are the design challenges that remain? Thermal management? Small form factors?

CHIAO: It seems intuitive that SDR should enable us to easily switch between different applications at the touch of a button, and it’s generally the case that this is where the technology is heading. The technical challenges necessary to meet these are varied, but generally relate to frequency, bandwidth, and processing capability. Frequency relates to the ability to effectively tune into a wide band of signals, which require the entire radio chain be designed to accommodate the amplification, filtering, and down/up conversion of signals across the entire band of operation. This can present some engineering challenges, but this job has been made considerably easier by recent advances in semiconductor technology.

Different applications and interfaces may have significantly different bandwidth requirements; for example, supporting the latest WiFi protocol might require over 40MHz of bandwidth, but a voice radio channel might require less than 5kHz. Supporting this requires a more complicated architecture, which directly speaks to the thermal and form factor challenges you mentioned.

But the most substantial limiting factor is the available processing capability for embedded devices; stream processing is a computationally taxing effort that requires near real-time processing, which can sometimes push the limits of modern processing technology; this is definitely an area where clever thinking can work around some of the more substantial problems, but it nevertheless poses significant challenges.

UHM: There is no doubt that size, weight, and power (SWaP) is still a major issue in the implementation of tactical radio hardware. This is inclusive of thermal management, small form factor, battery life, ruggedness, and reliability. That being said, we should acknowledge that software also remains a big challenge. After all, moving the radio to software is the whole point behind SDR. Solutions are needed for more efficient programming of baseband processors, higher code portability between processors and platforms, and easier waveform and radio management.

MCHALE: Reduced SWaP requirements are creating challenges for designers of all military systems, not just radios. Future radios are bound to have a small form factor requirement, which puts pressure on engineers to pack more and more performance into a small footprint that will rely on commercial processing technology, which means more thermal management problems as these devices generate excessive amounts of heat.

MCHALE REPORT: Have smartphone capabilities converged with military SDR platforms? In other words giving warfighters similar functionality in their radios as they have in their personal cell phones.

UHM: One could ask if they have similar functionality in their radios as they do in their cell phones, and vice versa. On the one hand, cell phones are far more compact, can switch seamlessly between waveforms/air interfaces (i.e., LTE, WCDMA, WiFi, etc.), generally have better battery life, have nicer screens and have access to far more applications and content. I think most warfighters would agree that they don’t have enough cell phone capabilities in their tactical radios. On the other hand, cell phones are not capable of MANET (mobile ad hoc networking), which is absolutely critical functionality to have in an environment where there is no infrastructure. Without base stations, cell phones are not capable of communicating to each other. They are also generally not as secure. Although there are some commercial proxies for both, such as D2D (or direct mode) and AES encryption, they fall far short of the capabilities in today’s tactical radios. So, in short, while there is some convergence between the two worlds, there are still large functionality gaps between them.

CHIAO: Absolutely not; the convenience, features, processing power, and interface provided by a smart phone are so many orders of magnitude greater than anything available to soldiers. Even setting aside the radio, signal processing, protocol, encryption, and form factor requirements demanded of a military radio - all of which are fairly well defined and surmountable - a solider radio is generally limited to voice (and sometimes) data communications.

Now consider the singular utility provided by the camera on your smart phone. Or the ability to immediately find your location, and share it with your friends. Or not having to wait for the other guy to finish talking. Or a user interface that doesn’t require you to keep the user manual close by every time you want to set the time.

Commercial smartphone technology and applications have completely dwarfed military SDR platforms, and we continue to see significant improvements between generations that are two to three years apart. But it’s far from clear why this needs to be the case. More simply, there’s very little standing in the way of building a secure, customizable, and user-friendly package that preserves compatability with existing handsets and radios. It just hasn’t been done.

MCHALE: I often hear program managers and system integrators tell me that this or that general keeps demanding the same smartphone functionality his kids have with their iPhones for his warfighters. It’s a wonderful idea to be able to have ease of use of use and functionality of your cell phone with your radio on the battlefield, but at the moment it’s just not practical with the biggest roadblocks typically being security and ruggedization. Efforts are happening to develop rugged smartphone technology for military applications, many based on Android technology rather than Apple. Just making this capability practical for the warfighter is a couple years away let alone merging it into a tactical radio.

MCHALE REPORT: What is the next evolution for SDRs? Cognitive radio, or something else? Predict the future.

CHIAO: Actually delivering and executing on the original promise of providing a common hardware platform that easily allows users to switch between different applications. Delivering on that promise means we can easily take advantage of all the other benefits associated with traditional software platforms, including ongoing performance improvements and features.

UHM: SDRs have already evolved into cognitive radios in many markets. From a military perspective today, most tactical radios, SIGINT, EW, and radar systems are also cognitive radios that are capable of transmitting and capturing data across a wide bandwidth of RF frequency. So this is really a given. Market trends towards the integration of analog and digital ICs will only reinforce this evolution, and also move cognitive radio into more commercial markets by reducing cost and SWaP. In addition, I think the industry is ripe for far more software innovation. Better development tools for heterogeneous processing, software defined networking, and machine learning will hopefully have a radical impact, leading to smarter radios that are far more SWaP friendly than today.

MCHALE: The market for SDR technology for U.S. military applications should be a steady investment for the military. In an article on the military electronics market I wrote this month analysts at Technavio in Elmhurst, Illinois, see increased requirements driving the global military mobile-computing systems market over the next five years. They forecast the market to grow at a compound annual growth rate (CAGR) of more than 7 percent by 2020.

As for future applications, systems integrators are starting to take a look at SDR for not only cognitive radio, but for use in spectrum management applications and to improve operations in anti-access/area denial (A2/AD) environments, as Mike Jones, Vice President and General Manager of Rockwell Collins Communication and Navigation told me in this interview last year.