Military Embedded Systems

Modular Open Systems Approach for weapons systems is a warfighting imperative


November 20, 2019

John Bratton

Mercury Systems

The recent tri-service memorandum requiring modular open system approaches (MOSAs) to be deployed in all future defense systems is aimed at putting the best technology into the hands of the warfighters faster. Take a look at how designers are meeting tri-service requirements by moving past commercial off-the-shelf (COTS) to MOSA.

The memo

In early 2019, all service acquisition execu­tives and program executive officers received a memorandum from the tri-­service secretaries (Office Secretaries of the Navy, Army, and Air Force). Dated January 7, the subject read, “Modular Open Systems Approaches for our Weapon Systems is a Warfighting Imperative.”

The single-page document was succinctly summarized by two consecutive sentences: “We determined the continued implementation of these standards, and further development of Modular Open Systems Approach (MOSA) standards in areas where we lack them is vital to our success. As such, MOSA supporting standards should be included in all requirements, programming and development activities for future weapon system modifications and new start development programs to the maximum extent possible.”

The memorandum’s message is clear: Our defense systems need a modular open systems approach so that the best available technology can be delivered to war­fighters faster than our near-peer competitors can get it. SOSA [Sensor Open Systems Architecture], OMS/UCI [Open Mission Systems/Universal Command and Control Interface], FACE [Future Airborne Capability Environment], and VICTORY [Vehicular Integration for C4ISR/EW Interoperability] were highlighted as hardware and software processing MOSAs that would qualify. (Figure 1.)

Figure 1 | Common MOSAs and their initial sponsors.



A history of COTS and MOSA

Since the early 1990s and the commercial off-the-shelf (COTS) technology initiative headed by Department of Defense (DoD) secretary William Perry, the DoD has endeavored to leverage the best commercially developed technology, which is often based on open system approaches for affordability, adaptability, scalability, and interoperability.

The COTS initiative was originally centered almost solely around affordability, but increasingly it’s been found that COTS is required to reach the performance, interoperability, and quick reaction capability found in commercial marketplaces.

To maintain leadership, defense equipment must be produced with the capability and velocity of commercially developed open systems approach technology, even though the defense industry often has other special requirements and characteristics. Regardless, as former Defense Secretary Ash Carter said several years back to the Senate Appropriations Committee, “Future success will go to the fastest innovators. Leading the race now depends on who can out-innovate (and deploy) the fastest.”

For more than twenty years now, the DoD has increasingly embraced COTS; now, as underscored by the tri-service memo directing the procurement requirements necessary to keep a technological separation between our warfighters and our competitors, MOSAs are leveraging the best commercial technology available.

MOSA convergence

DoD-initiated MOSAs share a common premise on how to place the best contemporary technology in the hands of the warfighter more effectively and efficiently. This starting point enables these approaches to increasingly complement and augment each other, and ultimately to converge. SOSA in particular is becoming an umbrella for other MOSAs (Figure 2). SOSA accommodates HOST [Hardware Open Systems Technologies] and CMOSS [C4ISR/EW Modular Open Suite of Standards] approaches. CMOSS, in turn, accommodates FACE, MORA [Modular Open RF Architecture], VICTORY, and the RedHawk Linux operating system.

Figure 2 | SOSA, in particular, is becoming an umbrella for other MOSAs.



Standards convergence is often inevitable. For the defense industry, it is very timely as near-peer competitors using agile commercial technology are emerging faster than ever.

What’s in it for everyone?

SOSA defines the architecture, electrical/mechanical, hardware, software, and interfaces for radar, signals intelligence, EO/IR, electronic warfare (EW), position/­navigation­/timing (PNT), and communications processing. It has been adopted by the U.S. Army, Navy, and Air Force and features interoperability with FACE, OMS, SPIES [an aerospace sensor standard], MORA, Redhawk OS, CMOSS, VICTORY, and VITA [VME International Trade Association] standards. SOSA includes a holistic sensor management framework, has built-in security, and is packaged within a business model to ensure that the DoD, warfighters, prime contractors, and industry all get what they need to succeed.

The SOSA approach decomposes existing infrastructures and recomposes them as more capable and adaptable solutions made from common, interoperable building blocks. The effectiveness of this approach is defined by the benefits it delivers, which are measured in terms of the time taken to implement new missions – from the current months and years to weeks or even days depending upon the type of mission.

Moving at the speed of technology

Many common DoD-initiated MOSAs are not in fact new: They are more “standards of standards” which define and incorporate the best existing, proven, and evolving (active) standards and adopt them. VITA and its rugged OpenVPX ecosystem of ­digital – and increasingly RF and performance standards – is common to many of the DoD open approaches. This enables them to evolve at the speed of technology as the underlying standards like OpenVPX evolve in step with industry.

SOSA offers stakeholders six basic capabilities that place the best technology in the hands of warfighters quicker and more efficiently. With SOSA:

  • Rapid technology insertions enable equipment to be updated at the speed of technology
  • Reductions in size, weight, and power (consumed) of processing systems enables platforms to go longer, farther, and higher and carry more powerful processing payloads
  • Reductions in sustainment costs enable more and better systems to be deployed
  • Increased competition drives affordability and innovation
  • Enhanced compatibility enables systems to scale across platforms and domains
  • Improved cybersecurity enables systems to become more resilient to attacks

Rapid technology insertion

SOSA creates the ability to insert new technology that addresses emerging requirements, and to reuse existing capabilities from industry, science, technology and other programs. Specifically, SOSA seeks to standardize flight-line configurability and card-edge interoperability through:

  • Standard form factors, connectors, and pinouts that facilitate physical integration
  • On-the-wire interfaces for discovery, management, health monitoring, and data sharing
  • Software/firmware frameworks enabling portability, reuse, and reprogrammability
  • Modularity and partitioning to reduce regression testing

This standardization allows, for example, Army Program X to integrate an application from Air Force program Y that addresses a new signal of interest, or Navy “Program Z” to use a COTS plug-in card that provides additional processing capability – all with little or no modification.

Reduce size, weight, and power

SOSA seeks to reduce the size, weight, and power (SWaP) footprint of C5ISR [command, control, computers, communications, cyber, intelligence, surveillance, and recon­naissance] systems through:

  • Functional decomposition with well-defined interfaces that enable hardware and software sharing while reducing unnecessary redundancy
  • Simplified integration kits (e.g., cables and mounts)
  • Shared data services
  • Frameworks definitions that enable software capabilities to be deployed on existing hardware

Examples include pooled RF resources (amplifiers and antennas); capabilities deployed as cards in a common chassis; network-based position, navigation, and timing (PNT) services; and multiple applications hosted on the same processor.

Lower sustainment costs

SOSA encourages economies of scale by using common hardware, reducing the size of the logistics tail by using interoperable spares, and removing lifetime buys by enabling hardware modernization every five to 10 years. Specific enablers include:

  • Standard form factors, connectors, and pinouts for interoperable hardware elements
  • Software and firmware frameworks and/or runtime environments to load operational software on “generic” hardware elements

When implemented, success may include the ability to use the same SBC across Army, Air Force, and Navy programs plus the ability to upgrade to the latest technology as processors fail, become obsolete, or are no longer available.

Increased competition

SOSA fosters healthy competition and innovation during the systems acquisition and sustainment phases of defense programs of record through:

  • Functional decomposition that enables the re-integration of the best-of-breed capabilities
  • Open interfaces that remove vendor lock and proprietary integration
  • Fully defined interfaces that enable integration of “black box” software and hardware modules
  • Clear conformance criteria and certification processes

Increased competition and decomposition enables independent competes for subsystems, such as front-end apertures/back-end processing subsystems and the ability to integrate novel capabilities from third parties.

Enhanced compatibility

SOSA seeks to minimize interferences between sensor systems running concurrently on a platform, while ensuring availability of high-priority missions through:

  • Resource management that reserves and schedules shared resources
  • Messaged interconnects that retrieve system configuration information
  • Quality of service at sensor interconnections
  • The ability to plan, prioritize, and preempt missions

When implemented, SOSA compatibility enables conflict-free communications, EW, SIGINT [signals intelligence], and radar operation in the same RF spectrum that dynamically adjusts spectrum usage based on ambient environment conditions and mission needs.

Improved cybersecurity

SOSA seeks to ensure system integrity by any avenue that would compromise sensitive mission data by controlling access to shared modules and subsystems through:

  • Cybersecurity controls that verify authentication, authorization, integrity, and confidentiality
  • Separate security enclaves that enable missions to operate at different classification levels using the same sensor

Successfully implemented, SOSA strives to prevent exfiltration of data over RF transmitters and physical and logical measures to prevent unauthorized users (human or machine) from using the system, while encrypting all classified data at rest and user data before transmission over airways.

Investing in the warfighter

This is a critical time for the defense industry as it evolves faster than ever during peacetime to support war­fighters operating in a complex world that is evolving as quickly as technology. Adopting the best commercial technology depends on the DoD to retool faster and more effectively through the use of modular open system approaches.

John Bratton is Director of Product Marketing for Mercury Systems. He has more than 25 years of experience in embedded packaging, interconnect, and RF. Mr. Bratton earned his bachelor’s degree in MechEng from the North Eastern University of England and is a member of IMechE and ASME.

Mercury Systems


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