Wireless Innovation Forum contributions to SCA 4.1

Story

October 09, 2014

“The SCA Specifications are an important cornerstone to SDR Standardization, and…a prerequisite to enable timely and cost efficient porting and integration of waveforms, especially multinational and secure waveforms for combined operations,” said Dr. Ruediger Leschhorn, Head of Studies in the Radio Communications Division of Rohde & Schwarz, Germany.

The SCA 2.2.2 architecture has achieved significant success in the military communications market1. Hundreds of thousands of SCA-enabled software-defined radios (SDRs) have been deployed to date, and dozens of programs are currently working to field more of these types of radios moving forward (see lead image). The reasons for this success lie in the benefits brought through adoption of the SCA: proven cost and delivery-time advantages, enhanced intercomponent interoperability, simplified insertion of new communications capabilities in deployed radios, and reduced development risk and time to market. The success of the SCA to date has led new countries and new organizations to begin exploring its use, driving a second generation of SDR market adoption2.

As with any technology, actual use in real-world environments highlighted the improvements in the SCA specification that were necessary to allow further market penetration. Chief among these were improving the ability of the architecture to scale to address the size, weight, power, and cost requirements of certain radios; finding modifications in the architecture that could enable radios to boot faster; improving support for devices such as digital signal processors (DSPs) and field-programmable gate arrays (FPGAs) that are used in most radio architectures; and enhancing the ability to migrate legacy waveforms to an SCA model. The need for these improvements led programs such as the European Secure Software Defined Radio (ESSOR) program in Europe to define their own SCA-based SDR architectures3.

New specification needed

In 2009, the Joint Program Executive Office for the Joint Tactical Radio System (JPEO JTRS) initiated the SCA Next project to provide these improvements. The Wireless Innovation Forum brought the voice of the international community to the collaboration process, providing contributions from member organizations worldwide and from programs such as ESSOR4,5,6,7. The result of these and other efforts was SCA 4.0, which provided improved scalability and better support for lightweight applications by removing the requirement for Common Object Request Broker Architecture (CORBA) middleware and defining lightweight and ultra-lightweight environments for development on resource-constrained processors8.

In November 2013 the evolution of the SCA continued through a workshop hosted by the Wireless Innovation Forum’s Coordinating Committee on International SCA Standards (CCSCA) and with participation from the JTNC to further improve the SCA specification9. Key areas for additional improvement defined at this workshop included better backwards compatibility with SCA 2.2.2 and additional updates to the Application Environment Profiles (AEPs) and Interface Definition Language (IDL) profiles. A work plan was established, with the Wireless Innovation Forum taking the lead in developing technical solutions in multiple areas.

Technical contributions to SCA 4.1

Well over 1,000 hours were volunteered by the Forum’s member representatives in developing these solutions. Their efforts resulted in six recommendations10:

• Application-Backwards Compatibility. This recommendation provides comments on the modifications to SCA 4.0 necessary to support application-backwards compatibility with SCA 2.2.2.
• Application Mixture. This recommendation proposes changes to the next SCA specification, which will allow an application to be comprised of both SCA 2.2.2 and SCA 4.1 components. This change will allow developers to perform a more incremental transition from SCA 2.2.2 to SCA 4.
• Naming Conventions. This recommendation proposes changes to the SCA 4.0.1 specification to use a naming convention for the names of the interfaces and components. The goal is to improve readability of the next release of the specification.
• Push Registration Allocation Properties. This recommendation proposes changes to the SCA 4.0.1 specification to support late device registration with the domain manager. This change will allow the core framework to better accommodate device components with multiple implementations and to manage plug and play devices.
• Scalable Components. This recommendation proposes changes to the SCA 4.0.1 specification to improve component scalability by allowing component developers to choose whether or not to implement some of the standard subcomponent interfaces. The scalability will also be used to support the different profiles of the specification (see Figure 1).
• Scalable Manager Components. This recommendation proposes changes to the SCA 4.0.1 specification to add support for scalability of the manager components. This will allow developers to choose whether or not to implement all of the manager interfaces. The manager scalability will also be used to support the different profiles of the specification.

 

Figure 1: Proposed Component Base UML model.

 

The volunteer efforts also produced two specifications11. The first is WInnF Lw & ULw AEPs. This specification defines POSIX AEPs for interaction between SDR applications and the operating environment (OE) in resource-constrained architectures. Two Base AEPs functions groups, the Lightweight (Lw) and the Ultra-Lightweight (ULw), are defined. The documents contain normative content for Base AEP functions groups plus support sections giving SCA-like contents-overview tables and detailed rationale for the design choices. The specification also provides two function groups that can extend the Base AEPs function groups if required for porting, with negligible impact on portability. The specification harmonizes and improves prior work from JTNC and ESSOR into a single converged solution (see Figure 2).

 

Figure 2: Positioning the AEP specification.

(Click graphic to zoom by 1.9x)

 

The second spec is the WInnF PIM IDL Profiles. This specification defines platform-independent model (PIM) IDL profiles that may be used to define platform-independent SDR component APIs. Two PIM IDL profiles are defined: the “Full” and the “Ultra-Lightweight” profiles. The document contains normative content for the defined profiles, a support section with content-overview tables and extension perspectives, and a rationale section to explain the design choices. This specification also harmonizes and improves prior work from JTNC and ESSOR into a single converged solution.

Where to next?

The document packages above have been submitted to the JTNC for consideration to be included in the SCA 4.1 specification. At the time of this writing, a release date for this new specification has not yet been defined, but it is anticipated that a draft will be available late in 2014 or early 2015. In the interim, a preview event has been scheduled for October to present the proposed changes and to explore requirements for future SCA updates12.

Lee Pucker is the CEO of The Wireless Innovation Forum, a non-profit “mutual benefit corporation” dedicated to advocating for the innovative use of spectrum, and advancing radio technologies that support essential or critical communications worldwide. Lee is a certified association executive (CAE), a project management professional (PMP), and holds a BSc degree from the University of Illinois and an MSc degree from The Johns Hopkins University. Readers may reach him at [email protected].

Wireless Innovation Forum 604-828-9846 www.wirelessinnovation.org

References

1 http://groups.winnforum.org/d/do/6610

2 http://groups.winnforum.org/d/do/6527

3 http://www.occar.int/296

4 http://jtnc.mil/sca/Documents/JPEO-NR-2010-004.pdf

5 http://groups.winnforum.org/d/do/4983

6 http://groups.winnforum.org/d/do/4984

7 http://groups.winnforum.org/d/do/4985

8 http://jtnc.mil/sca/Pages/default.aspx

9 http://groups.winnforum.org/p/cm/ld/fid=403

10 http://groups.winnforum.org/Recommendations

11 http://groups.winnforum.org/Specifications

12 http://www.wirelessinnovation.org/sca-4-1-standard-preview-event