The next generation of open-systems embedded computing standards

Feb. 22, 2023

The Sensor Open System Architecture (SOSA) technical standard for embedded computing hardware and software is moving beyond its initial promises of reducing development and integration costs and time to field for military electronics designs, and is beginning to provide tangible benefits for early adopters who are seeing the new standard take hold in a big way.

The Open Group in San Francisco published the Technical Standard for SOSA Reference Architecture, Edition 1.0, in fall 2021, which paves the way for embedded computing companies to prove by documentation that they meet SOSA's guidelines -- not merely claim to be in alignment with the spirit of the new standard.

Now the embedded computing industry has a plan to follow, and later this year will have established procedures for certifying computing components as
conformant with SOSA guidelines with a conformance test suite that will evolve over time to cover components ranging from chassis and enclosures, to power conditioning and control, and eventually to software components.

The aim of SOSA

"Right now SOSA is probably the most influential standard out there," says Steve Edwards, director of secure embedded computing solutions for the Curtiss-Wright Corp. Defense Solutions division in Ashburn, Va. "It is the one that is most active, and that has involvement from the government -- particularly the Army and Air Force -- and SOSA is starting to incorporate some other industry standards."

For the most part, SOSA doesn't aim at creating a new standard, but instead seeks to incorporate as many accepted industry standards as possible, so as to avoid re-inventing the wheel and to use standards with which industry designers already are familiar. SOSA, for example, has adopted the OpenVPX standard of the VITA Open Standards, Open Markets trade association in Oklahoma City. SOSA has begun adopting the U.S. Army's Vehicle Integration for C4ISR/EW Interoperability (VICTORY) standard, industry experts say, and is expected to adopt additional standards in the future.

"SOSA is a standard of standards," says Mark Littlefield, senior manager of embedded computing products and solutions at Elma Electronic in Alameda, Calif., and is co-chair of the SOSA small-form-factor subcommittee. "The more standards that collaborate, the better the SOSA ecosystem. It's also about supporting what is already out there, and having the tie-in to what is already out there will strengthen SOSA as a choice."

The spirit of SOSA reflects a desire to develop new standards only when necessary, and rely instead on established standards. "The SOSA mandate is to adopt,
adapt, and develop," says Dominic Perez, chief technology officer at Curtiss-Wright Defense Solutions. "If they don't have to create something new, then don't, if they can pull in from existing standards. When it doesn't fit the use case, then they want to adapt and modify those existing standards."

One example involves the VITA OpenVPX standard. "There are things where SOSA has defined VPX profiles outside of VITA, and then VITA wants to roll those profiles back into OpenVPX," Perez says. "They are trying to create as little as possible, and adopt as much as they can."

Ultimately SOSA isn't intended to be a standard so comprehensive as to cover every conceivable design challenge. "SOSA isn't a be-all spec; it's an 80-percent spec., and 20 percent will be application-defined," says William Pilaud, director of systems architecture at LCR Embedded Systems Inc. in Norristown, Pa. "It makes it easier on the integrators as they try to help people out."

Overall, SOSA seeks to enable rapid, affordable, cross-platform best practices for systems, software, hardware, electrical, and mechanical engineering. It is intended to reduce development and integration costs for military capabilities and reduce time to field. The standard encapsulates fundamentals of the Modular Open Systems Approach (MOSA) design approach to develop embedded computing solutions for military applications that involve a unified set of sensor capabilities.

The SOSA Consortium aims to create a common framework for moving electronics and sensor systems to an open-systems architecture based on key interfaces and open standards established by industry and government consensus to support aerospace and defense applications for manned and unmanned surface vessels, submarines, aircraft, land vehicles, and spacecraft. The goal is to reduce development and integration costs and reduce time to field new sensor capabilities.

Demonstrated benefits

Perhaps the best news about SOSA is how the standard is starting to have tangible benefits for the companies that have embraced it. "The prime contractors see that using SOSA will sweeten their offers to the government, because SOSA will make their bids more attractive," says Rodger Hosking, director of sales at the Mercury Systems facility in Upper Saddle River, N.J.

Early adopters may be seeing some surprises, but overall see SOSA as worth it to help achieve plug-and-play interoperability among products from different vendors, drive down embedded computing costs, and make rapid systems upgrades a reality.

"In some cases SOSA will add some cost because of the backplane RF connectors where all the RF signals must go through the backplane," Mercury's Hosking explains. "Those connectors and housings are expensive, and add cost to the system, but you could argue about the savings they offer in reliability and maintenance, compared to front-panel interconnects."

The benefits can outweigh the drawbacks, Hosking says. "that extra cost really does provide a meaningful benefit that everyone agrees with," he says. "A lot of what SOSA mandates is based on common sense, and is done for a very deliberate reason. People are making really good arguments about why SOSA should be a military mandate."

Despite the up-front costs, Mercury customers are buying-in to the long-term benefits of SOSA, Hosking says. "We are selling a lot of this SOSA flavor to our customers, and the trend they see is they want to be ready when and where SOSA is mandated, and might want to provide that backplane analog RF I/O so their customers see that as a benefit. SOSA is good technology, whether it is mandated or not."

Interoperability among different companies' SOSA-aligned products no longer is just a claim; it's demonstrated reality, says LCR's Pilaud. "Now that availability of components are getting aligned, at LCR we have the ability to do a lot of mix-and-match between vendors, get standardized, and get the I/O path defined."

Those factors can help LCR and other embedded computing companies expand their product offerings to customers who no longer have anxiety that these products will be compatible. "We can offer baseline backplanes and systems that can plug and play, and we are almost at that point where I have two customers who had different boards from different vendors, but backplane commonality is almost 100 percent. Then I could offer the same enclosures to two different customers," Pilaud says. "We will start offering more and more integrated systems that customers can get 80 percent of what they need -- and if we get lucky 100 percent of what they need. That's what I've seen in the past two years."

Pilaud and other embedded experts are not under the illusion that SOSA has the potential to cover all their solutions, but what the standard offers will be enough.
"Are we there where every I/O or every program has completely standardized?" Pilaud asks "No, we are still a ways away, and that is because there are so many types of programs and architectures out there. Radar looks different from communications or electronic warfare. In time we will have a lot of reference architectures. We are standardized at the backplane and the I/O panel. SOSA has enough benefit that having at least some subset of it has extraordinary benefits."

Not all the measurable benefits of SOSA are technological; there are business advantages, too, says Valerie Andrew, strategic marketing manager for Elma Electronic. "One subset of SOSA is focusing on documentation for acquisition," Andrew says. "We are getting ready to release a document for acquisition people to follow that talks about what kind of language to use in requests for information and requests for quote, and to call out for acquisitions that support developing products in SOSA."

How SOSA is evolving

SOSA 1.0 was published on 30 Sept. 2021, and the next iteration, SOSA 2.0, should be published sometime this spring, says Ilya Lipkin, chair of the SOSA Steering Committee for the Open Group, and an open-architecture technical expert for the U.S. Air Force Life Cycle Management Center at Wright-Patterson Air Force Base, Ohio. "Hopefully we will publish SOSA 2.0 within the next couple of months," Lipkin says. "Most of the work is completed."

Since SOSA 1.0 was published, and even before, "we have got an industry adoption," Lipkin says. As far as organizations that have joined the SOSA consortium since its inception, "we were hoping for 10 to 15 companies." Today the consortium has 144 companies -- and counting. Among the most influential organizations in the consortium are the Air Force Life Cycle Management Center; Boeing; Collins Aerospace; Lockheed Martin; U.S. Naval Air Systems Command; the U.S. Space Force Space and Missile Systems Center; and U.S. Army PEO Aviation. A list of SOSA Consortium members is online at

As far as the entire SOSA standard is concerned, Lipkin says the consortium is "halfway through technical standard development, and in the next year we could be 80 to 100 percent complete. We are trying to keep solutions as close to the speed of COTS as possible."

The future of SOSA is somewhat sketchier. "Where we are headed is a moving target," Lipkin admits. "We need to keep the commercial market as close as possible. We have started small form factors in SOSA recently for smaller than 3U designs. Those are low-cost, large-volume products. For small scale capabilities. this is one of those big game changers."

Lipkin predicts that SOSA-conformant small-form-factor embedded computing boards should be available on the open market within two or three years. These boards will be smaller than 3U OpenVPX boards.

Among the most pressing technology challenges for SOSA in the future will be countering the effects of heat in high-performance embedded computing systems. "in the future we always will be  battling hot components from Intel, NVIDIA, and the FPGAS [field-programmable gate arrays]," says LCR's Pilaud. "It puts a challenge on the form factor of how to cool effectively. I would say we have a few form factors like liquid and air flow through technologies on the VITA side to help, but I don't know if we are really there yet."

Another future challenge of SOSA will involve dealing with extremely high-bandwidth processors for applications like signals intelligence, electronic warfare and radar signal processing, Pilaud adds.

Conformance testing

The next great stage in the evolution of SOSA is setting up and carrying out conformance testing to certify SOSA-conformant products. "There is a whole group within SOSA working on the conformance guide, which will be that go-to thing to tell you what the company has to do to be conformant to SOSA," says Elma's Littlefield.

This conformance guide "will help people understand the conformance process, with tools of what they need to do, and help guide them through the process," explains Ken Grob, director of embedded technology at Elma. The conformance guide will help companies "understand how much of this mumbo-jumbo do I have to do, and what is it going to cost me," Grob says. "There is confusion understanding when and how to achieve conformance." The first version of the SOSA conformance guide is expected to be available by the end of February 2023.

"Verification isn't only test," cautions Elma's Littlefield. "It involves inspection, analysis, and test. There is a fair amount of analysis required  for design materials, and even checking to see if something exists in a product or not. Inspection is does it have the necessary feature. Analysis is looking at the design is does it meet the expectations."

Early SOSA conformance testing "will be very inspection-heavy because we don't have an established conformance infrastructure," Elma's Littlefield says, adding that the first SOSA conformance testing is expected to happen sometime this fall.

"In a nutshell the conformance program is one of those critical aspects of SOSA to ensure interoperability; we're all about fast fielding, says the Air Force's Lipkin. "The initial release of the conformance program will be in the next couple of months, and it will be incrementally released." Initial SOSA conformance testing most likely will involve hardware components, with the more difficult software aspects coming later.

Many details about SOSA conformance testing have yet to be determined, but Lipkin says the process "needs to be cheap, and we need to automate it to the maximum extent possible. It needs to have cheap enough tooling so vendors can integrate conformance testing as part of their development process.

The Open Group is expected to list companies that receive SOSA product certification on the organization's website at "It will be a short list at first," points out Elma's Andrew.

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